publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2012-08-11 | Suppression of backward scattering of Dirac fermions in iron pnictides Ba(Fe$_{1-x}$Ru$_x$As)$_2$ | We report electronic transport of Dirac cones when Fe is replaced by Ru,
which has an isoelectronic electron configuration to Fe, using single crystals
of Ba(Fe$_{1-x}$Ru$_x$As)$_2$. The electronic transport of parabolic bands is
shown to be suppressed by scattering due to the crystal lattice distortion and
the impurit... | 1208.2328v2 |
2012-08-13 | Specific Heat Discontinuity DeltaC vs Tc in Annealed Ba(Fe1-xCox)2As2 | The low temperature specific heat of annealed single crystal samples of
Ba(Fe1-xCox)2As2 with compositions spanning the entire superconducting phase
diagram was measured. Effort was made to discover the best annealing schedule
to maximize Tc and minimize transition width in these samples. Values of
deltaC/Tc normalized... | 1208.2492v1 |
2012-08-16 | Filamentary superconductivity across the phase diagram of Ba(Fe,Co)$_2$As$_2$ | We show magnetotransport results on Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ ($0.0 \leq
x \leq 0.13$) single crystals. We identify the low temperature resistance step
at 23 K in the parent compound with the onset of filamentary superconductivity
(FLSC), which is suppressed by an applied magnetic field in a similar manner to
the ... | 1208.3352v1 |
2012-08-17 | Anisotropic resistivity of Na$_{1-δ}$Fe$_{1-x}$Co$_x$As | Temperature-dependent resistivity is studied in single crystals of
iron-arsenide superconductor Na$_{1-\delta}$Fe$_{1-x}$Co$_x$As for electrical
current directions along, $\rho_a (T)$, and transverse, $\rho_c (T)$, to the
Fe-As layers. Doping with Co increases stability of this compound to reaction
with the environment... | 1208.3646v1 |
2012-08-21 | Contrast of LiFeAs with isostructural, isoelectronic, and non-superconducting MgFeGe | Stoichiometric LiFeAs at ambient pressure is an 18 K superconductor while
isoelectronic MgFeGe is not, despite their extremely similar electronic
structures. To investigate possible sources of this distinctively different
superconducting behavior, we quantify the differences using first principles
density functional th... | 1208.4180v2 |
2012-08-22 | Chandra grating spectroscopy of three hot white dwarfs | High-resolution soft X-ray spectroscopic observations of single hot white
dwarfs are scarce. With the Chandra Low-Energy Transmission Grating, we have
observed two white dwarfs, one is of spectral type DA (LB 1919) and the other
is a non-DA of spectral type PG1159 (PG 1520+525). The spectra of both stars
are analyzed, ... | 1208.4478v1 |
2012-08-24 | Superconductivity Appears in the Vicinity of an Insulating-Like Behavior in CeO$_{1-x}$F$_{x}$BiS$_{2}$ | Resistive and magnetization properties have been measured in BiS$_2$-based
samples CeO$_{1-x}$F$_{x}$BiS$_{2}$ with a systematic substitution of O with F
(0 $<$ x $<$ 0.6). In contrast to the band structure calculations, it is found
that the parent phase of CeOBiS$_2$ is a bad metal, instead of an band
insulator. By do... | 1208.5000v1 |
2012-08-25 | Glassy Transition in the Vortex Lattice of Ba(Fe0.93Rh0.07)2As2 superconductor, probed by NMR and ac-susceptibility | By using Nuclear Magnetic Resonance and ac-susceptibility, the characteristic
correlation times for the vortex dynamics, in an iron-based superconductor,
have been derived. Upon cooling, the vortex dynamics displays a crossover
consistent with a vortex glass transition. The correlation times, in the fast
motions regime... | 1208.5142v4 |
2012-08-28 | Alternative route to charge density wave formation in multiband systems | Charge and spin density waves, periodic modulations of the electron and
magnetization densities, respectively, are among the most abundant and
non-trivial low-temperature ordered phases in condensed matter. The ordering
direction is widely believed to result from the Fermi surface topology.
However, several recent stud... | 1208.5701v2 |
2012-08-31 | Comparison of Gamow-Teller strengths in the random phase approximation | The Gamow-Teller response is astrophysically important for a number of
nuclides, particularly around iron. The random phase approximation (RPA) is an
efficient way to generate strength distributions. In order to better understand
both theoretical systematics and uncertainties, we compare the Gamow-Teller
strength distr... | 1208.6538v2 |
2012-09-03 | Growth and characterization of n-type electron-induced ferromagnetic semiconductor (In,Fe)As | We show that by introducing isoelectronic iron (Fe) magnetic impurities and
Beryllium (Be) double-donor atoms into InAs, it is possible to grow a n-type
ferromagnetic semiconductor (FMS) with the ability to control ferromagnetism by
both Fe and independent carrier doping by low-temperature molecular-beam
epitaxy. We de... | 1209.0250v1 |
2012-09-05 | A 57Fe Mössbauer Study Of Local Structure And Spin Arrangements In Antiferromagnetic NaFeAs | Detailed 57Fe M\"ossbauer spectroscopy measurements on superconducting NaFeAs
powder crystals have been performed. The 57Fe spectra recorded in the
paramagnetic temperature range (T > TN \approx 46 +/- 2 K) were discussed
supposing Fe2+ ions are located in distorted tetrahedral (FeAs4) polyhedra. Our
results reveal tha... | 1209.0924v2 |
2012-09-05 | High resolution reddening map in the direction of the stellar system Terzan 5 | We have used optical images acquired with the Hubble Space Telescope to
construct the first high-resolution extinction map in the direction of Terzan
5, a peculiar stellar system in the inner bulge of our Galaxy. The map has a
spatial resolution of 8" X 8", over a total FoV of 200" X 200". The absorption
clouds show a ... | 1209.0990v1 |
2012-09-10 | The reawakening of the sleeping X-ray pulsar XTE J1946+274 | We report on a series of outbursts of the high mass X-ray binary XTE
J1946+274 in 2010/2011 as observed with INTEGRAL, RXTE, and Swift. We discuss
possible mechanisms resulting in the extraordinary outburst behavior of this
source. The X-ray spectra can be described by standard phenomenological models,
enhanced by an a... | 1209.1918v1 |
2012-09-11 | The stratified evolution of a cool star | A low mass star usually experiences stratification and abundance anomalies
during its evolution. A 0.95 solar mass star with a metallicity Z = 0.004 is
followed from the main-sequence to the Horizontal Branch (HB). On the
main-sequence the larger effects of stratification may come from accretion as
was suggested in rel... | 1209.2403v1 |
2012-09-18 | Impurity states in multiband s-wave superconductors: analysis of iron pnictides | We examine the effect of a single, non-magnetic impurity in a multiband,
extended s-wave superconductor allowing for anisotropy of the gaps on the Fermi
surfaces. We derive analytic expressions for the Green's functions in the
continuum and analyse the conditions for the existence of sharp
impurity-induced resonant sta... | 1209.3835v2 |
2012-09-21 | Engineering Study of Sector Magnet for the Daedalus Experiment | The Daedalus experiment seeks to evaluate neutrino scattering effects that go
beyond the standard model. Modular accelerators are employed to produce 800 MeV
proton beams at the megawatt power level directed toward a target, producing
neutrinos. The Superconducting Ring Cyclotron (SRC) consists of identical
sectors (cu... | 1209.4886v1 |
2012-09-25 | Study of The Abundance Patterns in The Metal-Poor Stellar Stream | The chemical abundances of the metal-poor stars in the stellar stream provide
important information for setting constraints on models of neutron-capture
processes. The study of these stars could give us a better understanding of
r-process nucleosynthesis and chemical composition of the early Galaxy. Using
the updated m... | 1209.5505v1 |
2012-09-25 | Structural phase transition below 250 K in superconducting K$_{0.75}$Fe$_{1.75}$Se$_{2}$ | Vibrational properties of iron-chalcogenide superconductor
K$_{0.75}$Fe$_{1.75}$Se$_{2}$ with $T_{c}\sim$ 30 K have been measured by Raman
and optical spectroscopies over temperature range of 3-300 K. Sample undergoes
\textit{I4/m} $\to $ \textit{I4} structural phase transition accompanied by
loss of inversion symmetry... | 1209.5718v1 |
2012-10-02 | Graphene as a reversible spin manipulator of molecular magnets | One of the primary objectives in molecular nano-spintronics is to manipulate
the spin states of organic molecules with a d-electron center, by suitable
external means. In this letter, we demonstrate by first principles density
functional calculations, as well as second order perturbation thoery, that a
strain induced c... | 1210.0666v1 |
2012-10-03 | Atomically Controlled Epitaxial Growth of Single-Crystalline Germanium Films on a Metallic Silicide | We demonstrate high-quality epitaxial germanium (Ge) films on a metallic
silicide, Fe3Si, grown directly on a Ge(111) substrate. Using molecular beam
epitaxy techniques, we can obtain an artificially controlled arrangement of
silicon (Si) or iron (Fe) atoms at the surface on Fe3Si(111). The Si-terminated
Fe3Si(111) sur... | 1210.1027v1 |
2012-10-05 | Thermodynamics of Ising Spins on the Star Lattice | There is a new class of two-dimensional magnetic materials polymeric iron
(III) acetate fabricated recently in which Fe ions form a star lattice. We
study the thermodynamics of Ising spins on the star lattice with exact analytic
method and Monte Carlo simulations. Mapping the star lattice to the honeycomb
lattice, we o... | 1210.1675v1 |
2012-10-08 | Microwave absorption study of pinning regimes in $\bf Ba(Fe_{1-x}Co_x)_2As_2$ single crystals | Magnetic field dependent modulated microwave absorption (MMWA) measurements
have been carried out to investigate vortex pinning effects in single crystals
of the iron-based high-Tc superconductor Ba(Fe_{1-x}Co_x)_2As_2 with three
different cobalt doping levels of x = 0.07, 0.09, and 0.11. The dependence of
the MMWA hys... | 1210.2309v1 |
2012-10-09 | Spin Wave Excitations in AFe$_{1.5}$Se$_2$ (A=K, Tl): Analytical Study | We have analytically solved the spin wave excitations for the intercalated
ternary iron-selenide AFe$_{1.5}$Se$_2$ (A=K, Tl) in the $4\times 2$ collinear
antiferromagnetic order. It is found that there are one acoustic branch
(gapless Goldstone mode) and two gapful optical branches of spin wave
excitations with each in... | 1210.2668v1 |
2012-10-11 | Recent developments in the shell model Monte Carlo approach to nuclei | The shell model Monte Carlo (SMMC) approach provides a powerful method for
the microscopic calculation of statistical and collective nuclear properties in
model spaces that are many orders of magnitude larger than those that can be
treated by conventional methods. We discuss recent applications of the method
to describ... | 1210.3102v1 |
2012-10-11 | Thermopower of the Correlated Narrow Gap Semiconductor FeSi and Comparison to RuSi | Iron based narrow gap semiconductors such as FeSi, FeSb2, or FeGa3 have
received a lot of attention because they exhibit a large thermopower, as well
as striking similarities to heavy fermion Kondo insulators. Many proposals have
been advanced, however, lacking quantitative methodologies applied to this
problem, a cons... | 1210.3379v1 |
2012-10-17 | Ferromagnetic Quantum Critical Point in Heavy-Fermion Iron Oxypnictide Ce(Ru$_{1-x}$Fe$_x$)PO | We have performed ^{31}P-NMR measurements on Ce(Ru_{1-x}Fe_{x})PO in order to
investigate ferromagnetic (FM) quantum criticality, since heavy-fermion (HF)
ferromagnet CeRuPO with a two-dimensional structure turns to a HF paramagnet by
an isovalent Fe-substitution for Ru. We found that Ce(Ru_{0.15}Fe_{0.85})PO
shows cri... | 1210.4604v1 |
2012-10-17 | The spectrum of Fe II | The spectrum of singly-ionized iron (Fe II) has been recorded using
high-resolution Fourier transform and grating spectroscopy over the wavelength
range 900 {\AA} to 5.5 {\mu}m. The spectra were observed in high-current
continuous and pulsed hollow cathode discharges using Fourier transform (FT)
spectrometers at the Ki... | 1210.4773v1 |
2012-10-19 | Unique phase diagram with narrow superconducting dome in EuFe$_2$(As$_{1-x}$P$_x$)$_2$ due to Eu$^{2+}$ local magnetic moments | The interplay between superconductivity and Eu$ ^{2+}$ magnetic moments in
EuFe$_2$(As$_{1-x}$P$_x$)$_2$ is studied by electrical resistivity measurements
under hydrostatic pressure on $x=0.13$ and $x=0.18$ single crystals. We can map
hydrostatic pressure to chemical pressure $x$ and show, that superconductivity
is con... | 1210.5440v2 |
2012-10-26 | Bulk properties and electronic structure of PuFeAsO | Here we present bulk property measurements and electronic structure
calculations for PuFeAsO, an actinide analogue of the iron-based rare-earth
superconductors RFeAsO. Magnetic susceptibility and heat capacity data suggest
the occurrence of an antiferromagnetic transition at TN=50 K. No further
anomalies have been obse... | 1210.7251v1 |
2012-10-28 | Observation of charge accumulation and onsite Coulomb repulsion at transition metal impurities in the iron pnictides | We report a combined valence band photoemission and Auger spectroscopy study
of single crystalline Ca(Fe,Co)2As2 and Ba(Fe,TM)2As2 with TM=Ni or Cu. The
valence band photoemission data show directly that the TM-states move to higher
binding energies with increasing atomic number, contributing less and less to
the state... | 1210.7483v1 |
2012-10-30 | Physical parameters of three field RR Lyrae stars | Str\"omgren $uvby-\beta$ photometry of the stars classified as RR Lyrae stars
RU Piscium, SS Piscium and TU Ursae Majoris has been used to estimate their
iron abundance, temperature, gravity and absolute magnitude. The stability of
the pulsating period is discussed. The nature of SS Psc as a RRc or a HADS is
addressed.... | 1210.7886v1 |
2012-10-31 | Theory and Simulation of the diffusion of kinks on dislocations in bcc metals | Isolated kinks on thermally fluctuating (1/2)<111> screw, <100> edge and
(1/2)<111> edge dislocations in bcc iron are simulated under zero stress
conditions using molecular dynamics (MD). Kinks are seen to perform stochastic
motion in a potential landscape that depends on the dislocation character and
geometry, and the... | 1210.8327v2 |
2012-11-02 | One-step theory of fcc-bcc martensitic transformation | Martensitic transformation in steels is responsible for their very high
strength and has thus been studied for more than one century since the first
works of Martens. However, there is not yet simple physical theory. A rigorous
classification of the crystallographic subgroupoids (packets) of the KS
variants and the con... | 1211.0495v1 |
2012-11-02 | Polarized neutron reflectometry study of Fe16N2 with Giant Saturation Magnetization prepared by N Inter-diffusion in Annealed Fe-N Thin Films | We report a synthesis route to grow iron nitride thin films with giant
saturation magnetization (Ms) through an N inter-diffusion process. By post
annealing Fe/Fe-N structured films grown on GaAs(001) substrates, nitrogen
diffuses from the over-doped amorphous-like Fe-N layer into strained
crystalline Fe layer and faci... | 1211.0551v1 |
2012-11-06 | Calculation of the transport critical current density of c-axis textured 122 iron-based superconductors | The c-axis textured Sr1-xKxFe2As2 tapes produced by cold rolling and
post-annealing, could carry a high super-current over 2*104 A/cm2. However, the
magnitude is far from its maximum, because of the current obstacles associated
with various defects in the material. To predict the maximal transport critical
current dens... | 1211.1141v1 |
2012-11-06 | Anisotropies and Homogeneities of Superconducting Properties in Iron-Platinum-Arsenide Ca10(Pt3As8)(Fe1.79Pt0.21As2)5 | We report a study on the anisotropy of superconducting properties in single
crystalline Ca10(Pt4-{\delta}As8)(Fe1.79Pt0.21As2)5 with Tc ~13.6 K. Under a
field of 5 Oe, the sample reaches fully-diamagnetic state at ~10 K for H//c,
and ~8 K for H//ab, indicating the presence of slight inhomogeneities. The
magnetization m... | 1211.1221v2 |
2012-11-08 | Effects of nuclear medium and nonisoscalarity in extracting $sin^2θ_W$ using Paschos-Wolfenstein relation | We study the nuclear medium effects and nonisoscalarity correction in the
extraction of weak mixing angle sin$^2\theta_W$ using Paschos-Wolfenstein (PW)
relation. The calculations are performed for the iron nucleus. The results are
discussed along with the experimental result inferred by NuTeV collaboration.
The nuclea... | 1211.1817v2 |
2012-11-08 | Constraints of the compactness of the isolated neutron stars via X-ray phase-resolved spectroscopy | A model with a condensed iron surface and partially ionized hydrogen-thin
atmosphere allows us to fit simultaneously the observed general spectral shape
and the broad absorption feature (observed at 0.3 keV) in different spin phases
of the isolated neutron star RBS 1223. We constrain some physical properties of
the X-r... | 1211.1842v2 |
2012-11-08 | Closing the Window on Strongly Interacting Dark Matter | Constraints are placed on the spin-independent interaction cross section of
dark matter with regular matter by refining two methods. First, dark
matter--cosmic ray interactions are considered, wherein cosmic ray protons
collide with dark matter to contribute to the gamma ray sky. This constraint is
developed using the ... | 1211.1951v1 |
2012-11-12 | An orbital-selective spin liquid in a frustrated heavy fermion spinel LiV$_2$O$_4$ | The pronounced enhancement of the effective mass is the primary phenomenon
associated with strongly correlated electrons. In the presence of local
moments, the large effective mass is thought to arise from Kondo coupling, the
interaction between itinerant and localised electrons. However, in d electron
systems, the ori... | 1211.2844v1 |
2012-11-14 | Are There Any Stars Lacking Neutron-Capture Elements? Evidence from Strontium and Barium | The cosmic dispersion in the abundances of the heavy elements strontium and
barium in halo stars is well known. Strontium and barium are detected in most
cool, metal-poor giants, but are these elements always detectable? To identify
stars that could be considered probable candidates for lacking these elements,
I examin... | 1211.3427v1 |
2012-11-15 | Annealing, acid, and alcoholic beverage effects on Fe1+yTe0.6Se0.4 | We have systematically investigated and compared different methods to induce
superconductivity in iron chalcogenide Fe1+yTe0.6Se0.4 including annealing in
vacuum, N2, O2, I2 atmosphere, and immersing samples into acid and alcoholic
beverages. Vacuum and N2 annealing are proved to be ineffective to induce
superconductiv... | 1211.3491v1 |
2012-11-16 | Bicrystalline Grain Boundary and Hybrid SNS Junctions Based on Ba-122 Thin Films | To investigate the properties of iron-based superconductors, we examined
different kinds of Josephson junctions using Co-doped Ba-122 thin films. Based
on bicrystalline SrTiO3 substrates we prepared grain boundary (GB) junctions,
which showed clear Josephson effects. We present electrical measurements at
varying temper... | 1211.3879v1 |
2012-11-27 | Theoretical spectroscopy of realistic condensed matter systems | This thesis is devoted to ab initio calculations of ground and excited state
properties of different systems within density functional theory and time
dependent density functional theory. From the numerical point of view we
implemented an original method in the DP code to calculate the independent
particle response fun... | 1211.6270v1 |
2012-11-28 | Stability of xenon oxides at high pressures | Xenon, which is quite inert under ambient conditions, may become reactive
under pressure. The possibility of formation of stable xenon oxides and
silicates in the interior of the Earth could explain the atmospheric missing
xenon paradox. Using the ab initio evolutionary algorithm, we predict the
thermodynamical stabili... | 1211.6520v2 |
2012-11-28 | Nonlocal optical generation of spin and charge currents on the surface of magnetic insulators using total absorption and surface plasmons | We study the nonlocal spin and charge current generation in a finite metallic
element on the surface of magnetic insulators such as \tcb{yttrium iron garnet}
due to the absorption of the magnetic surface plasmon (MSP). Whereas a surface
plasmon is completely reflected by a metal, \tcb{an} MSP \tcb{can be} absorbed
\tcb... | 1211.6716v1 |
2012-12-02 | Lateral spin injection and detection through electrodeposited Fe/GaAs contacts | Efforts to achieve efficient injection of spin-polarized electrons into a
semiconductor, a key prerequisite for developing electronics that exploit the
electron's spin degree of freedom, have so far met with limited success. Here
we report experimental studies of lateral spin injection and detection through
electrodepo... | 1212.0258v1 |
2012-12-11 | Red Supergiant Stars as Cosmic Abundance Probes: II. NLTE Effects in J-band Silicon Lines | Medium resolution J-band spectroscopy of individual red supergiant stars is a
promising tool to investigate the chemical composition of the young stellar
population in star forming galaxies. As a continuation of recent work on iron
and titanium, detailed non-LTE calculations are presented to investigate the
influence o... | 1212.2649v1 |
2012-12-14 | Forward and inverse problems in fundamental and applied magnetohydrodynamics | This Minireview summarizes the recent efforts to solve forward and inverse
problems as they occur in different branches of fundamental and applied
magnetohydrodynamics. As for the forward problem, the main focus is on the
numerical treatment of induction processes, including self-excitation of
magnetic fields in non-sp... | 1212.3447v1 |
2012-12-15 | Calibration Systems of the ATLAS Tile Calorimeter | TileCal is the hadronic calorimeter covering the most central region of the
ATLAS experiment at the LHC. This sampling calorimeter uses iron plates as
absorber and plastic scintillating tiles as the active material. A
multi-faceted calibration system allows to monitor and equalize the calorimeter
response at each stage... | 1212.3676v1 |
2012-12-16 | Wetting dynamics on lyophilic solid surfaces patterned by lyophobic islands | A theory for wetting of structured solid surfaces is developed, based on the
delta-comb periodic potential. It possesses two matching parameters: the
effective line tension and the friction coefficient on the three-phase contact
line at the surface. The theory is validated on the dynamics of spreading of
liquid zinc dr... | 1212.3791v4 |
2012-12-18 | Time Reversal Invariant Topological Superconductivity and Majorana Kramers Pairs | We propose a feasible route to engineer one and two dimensional time reversal
invariant (TRI) topological superconductors (SC) via proximity effects between
nodeless extended s wave iron-based SC and semiconductors with large Rashba
spin-orbit interactions. At the boundary of a TRI topological SC, there emerges
a Krame... | 1212.4232v2 |
2012-12-18 | Experimental realization of dynamo action: present status and prospects | In the last decades, the experimental study of dynamo action has made great
progress. However, after the dynamo experiments in Karlsruhe and Riga, the
von-Karman-Sodium (VKS) dynamo is only the third facility that has been able to
demonstrate fluid flow driven self-generation of magnetic fields in a
laboratory experime... | 1212.4331v1 |
2012-12-21 | Structural and magnetic phase transitions in triclinic Ca10(FeAs)10(Pt3As8) | We report the structural and magnetic phase transitions of triclinic
Ca10(FeAs)10(Pt3As8). High-resolution X-ray powder diffraction reveals
splitting of the in-plane (a,b) lattice parameters at Ts ~ 120 K.
Platinum-doping weakens the distortion and shifts the transition temperature to
80 K in Ca10(Fe1-xPt_xAs)10(Pt3As8... | 1212.5531v1 |
2012-12-24 | Fabrication and transport properties of Sr0.6K0.4Fe2As2 multifilamentary superconducting wires | Seven-core Ag/Fe sheathed Sr0.6K0.4Fe2As2 (Sr-122) superconducting wires were
produced by the ex situ powder-in-tube (PIT) method. The relationship between
the cold-work deformation process and the superconducting properties of wires
were systematically studied. It was found that flat rolling can efficiently
increase t... | 1212.5873v1 |
2012-12-24 | Spin-state transition in the Fe-pnictides | We report a Fe K\beta x-ray emission spectroscopy study of local magnetic
moments in the rare-earth doped iron pnictide Ca_{1-x}RE_xFe_2As_2 (RE=La, Pr,
and Nd). In all samples studied the size of the Fe local moment is found to
decrease significantly with temperature and goes from ~0.9 \mu_B at T = 300 K
to ~0.45 \mu_... | 1212.5925v1 |
2013-01-02 | Discovery of the first Super-Lithium rich Beat Cepheid: V371 Per | Four high-resolution spectra of the double-mode Cepheid V371 Per, obtained
for the first time, showed the presence of the abnormally strong Li I 6707.76 A
line. Our analysis of the light element abundances indicates that the star did
not go through the evolutionary dredge-up stage. Large distance from the
galactic plan... | 1301.0199v1 |
2013-01-03 | Pair Breaking Caused by Magnetic Impurities in the High-T$_\text{C}$ Superconductor Bi$_{2.1}$Sr$_{1.9}$Ca(Cu$_{1-x}$Fe$_{x}$)$_{2}$O$_{y}$ | Conventional superconductivity is robust against the addition of impurities
unless the impurities are magnetic in which case superconductivity is quickly
suppressed. Here we present a study of the cuprate superconductor
Bi$_2$Sr$_2$Ca$_1$Cu$_2$O$_{8+\delta}$ that is intentionally doped with the
magnetic impurity, Fe. T... | 1301.0521v2 |
2013-01-11 | Perspectives of the disproportionation driven superconductivity in strongly correlated 3d compounds | Disproportionation in 3d compounds can give rise to an unconventional
electron-hole Bose liquid with a very rich phase diagram from a Bose metal,
charge ordering insulator to an inhomogeneous Bose superfluid. Optimal
conditions for the disproportionation driven high-T_c superconductivity are
shown to realize only for s... | 1301.2395v1 |
2013-01-11 | Terzan 5: a Fossil Remnant of the Galactic Bulge | Terzan 5 is a stellar system located in the Galactic Bulge, at a distance of
5.9 kpc. Recent discoveries show that it hosts two stellar populations with
different iron abundance ({\Delta}[Fe/H]=0.5). Such a large difference has been
measured only in {\omega} Centauri in the Galactic halo. Moreover no
anticorrelation is... | 1301.2436v1 |
2013-01-16 | NGC5694: another extra-galactic globular cluster | We discuss the chemical composition of six giant stars of the outer Halo
globular cluster NGC5694, through the analysis of UVES@FLAMES high-resolution
spectra. The cluster has an average iron content [Fe/H]=--1.83+-0.01,
solar-scaled [alpha/Fe] ratios and a very low Ba abundance
([Ba/Fe]=--0.71+-0.06). These anomalous ... | 1301.3606v1 |
2013-01-21 | Nanoscale Surface Element Identification and Dopant Homogeneity in the High-$T_c$ Superconductor Pr$_x$Ca$_{1-x}$Fe$_2$As$_2$ | We use scanning tunneling microscopy to determine the surface structure and
dopant distribution in Pr$_x$Ca$_{1-x}$Fe$_2$As$_2$, the highest-$T_c$ member
of the 122 family of iron-based superconductors. We identify the cleaved
surface termination by mapping the local tunneling barrier height, related to
the work functi... | 1301.4942v2 |
2013-01-22 | Quasi-two-dimensional non-collinear magnetism in the Mott insulator Sr$_2$F$_2$Fe$_2$OS$_2$ | The magnetism of Sr$_2$F$_2$Fe$_2$OS$_2$ was examined through neutron powder
diffraction and thermodynamic and transport measurements. Quasi-two-dimensional
magnetic order develops below $T_N$ = 106(2) K with an in-plane correlation
length exceeding 310 \AA\ and an out-of-plane correlation length of just 17(3)
\AA. The... | 1301.5056v1 |
2013-01-23 | Nodal superconductivity in isovalently substituted SrFe$_2$(As$_{1-x}$P$_{x}$)$_2$ pnictide superconductor at the optimal doping, $x=$0.35 | Temperature-dependent London penetration depth, $\lambda(T)$, was measured in
optimally - doped, $x=$0.35, as-grown ($T_c \approx$25 K,
RRR=$\rho(300K)/\rho(T_c)$=4.5) and annealed ($T_c \approx$35 K, RRR=6.4)
single crystals of SrFe$_2$(As$_{1-x}$P$_{x}$)$_2$ iron - based superconductor.
Annealing increases the RRR an... | 1301.5622v1 |
2013-01-24 | Superconductivity, Antiferromagnetism, and Neutron Scattering | High-temperature superconductivity in both the copper-oxide and the
iron-pnictide/chalcogenide systems occurs in close proximity to
antiferromagnetically ordered states. Neutron scattering has been an essential
technique for characterizing the spin correlations in the antiferromagnetic
phases and for demonstrating how ... | 1301.5888v1 |
2013-01-25 | Upper critical field of isoelectron substituted SrFe$_2$(As$_{1-x}$P$_x$)$_2$ | The upper critical field $H_{c2}$ of optimally doped iron-based
superconductor SrFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ ($x$ = 0.35, $T_c$ = 25 K)
was measured as a function of temperature down to 1.6 K for two principal
directions of magnetic field $H \parallel c$ and $H \parallel a$. Measurements
were performed in pulsed ... | 1301.6142v1 |
2013-01-27 | Angular-dependent upper critical field of overdoped Ba(Fe$_{1-x}$Ni$_x$)$_2$As$_2$ | In-plane resistivity measurements as a function of temperature, magnetic
field and its orientation with respect to the crystallographic $ab-$plane were
used to study the upper critical field, $H_{c2}$, of two overdoped compositions
of the iron-based superconductor Ba(Fe$_{1-x}$Ni$_x$)$_2$As$_2$, $x=$0.054 and
$x$=0.072... | 1301.6396v1 |
2013-02-02 | Rethinking Globular Cluster Formation | This paper is aimed at emphasizing some of the main hints, constraints and
difficulties we currently have in trying to understand how globular clusters
formed, along with their multiple stellar generations, an issue that must be
regarded as intimately connected to the formation process itself. Thus, the
topics that are... | 1302.0329v1 |
2013-02-04 | Ferromagnetic Quantum Critical Point Induced by Tuning the Magnetic Dimensionality of the Heavy-Fermion Iron Oxypnictide Ce(Ru$_{1-x}$Fe$_x$)PO | We have performed 31P-NMR measurements of the c-axis-aligned poly-crystal
Ce(Ru1-xFex)PO with a two-dimensional layered structure in order to understand
the origin of TCurie suppression by Fe substitution. The variation in the
magnetic-fluctuation character with respect to x is investigated from the
in-plane and out-of... | 1302.0578v2 |
2013-02-05 | Type II superconductivity in SrPd2Ge2 | Previous investigations have shown that SrPd2Ge2, a compound isostructural
with "122" iron pnictides but iron- and pnictogen-free, is a conventional
superconductor with a single s-wave energy gap and a strongly three-dimensional
electronic structure. In this work we reveal the Abrikosov vortex lattice
formed in SrPd2Ge... | 1302.1022v1 |
2013-02-06 | Gap Symmetry and Stability Analysis in the Multi-Orbital Fe-Based Superconductors | The iron-based superconductors allow for a zoo of possible order parameters
due to their orbital degrees of freedom. These order parameters are often
written in an orbital basis, as this allows to distinguish their different
symmetry. Unlike in standard single-band superconductors, where electrons of
the same band - an... | 1302.1468v2 |
2013-02-07 | Evidence of Strong Correlations and Coherence-Incoherence Crossover in the Iron Pnictide Superconductor KFe2As2 | Using resistivity, heat-capacity, thermal-expansion, and susceptibility
measurements we study the normal-state behavior of KFe2As2. We find that both
the Sommerfeld coefficient gamma = 103 mJ mol-1 K-2 and the Pauli
susceptibility chi = 4x10-4 are strongly enhanced, which confirm the existence
of heavy quasiparticles i... | 1302.1696v1 |
2013-02-13 | Ligand field parameters and the ground state of Fe(II) phthalocyanine | A judicious analysis of previously published experimental data leads one to
conclude that the ground state of iron(II) phthalocyanine is an orbitally
degenerate spin triplet $a_{1g}^2 e_g^{\uparrow\downarrow\uparrow}
b_{2g}^{\uparrow}$ ($^3E_g$). The ligand field parameters, in relation to
Racah's $C$, are approximatel... | 1302.3023v2 |
2013-02-13 | Nucleosynthesis in the gamma-ray burst accretion disks and associated outflows | We investigate nucleosynthesis inside the gamma-ray burst (GRB) accretion
disks formed by the Type II collapsars and outflows launched from these disks.
We deal with accretion disks having relatively low accretion rates: 0.001 M_sun
s^{-1} <~ Mdot <~ 0.01 M_sun s^{-1} and hence they are predominantly advection
dominate... | 1302.3067v1 |
2013-02-13 | Unconventional Superconductivity | A brief review of unconventional superconductivity is given, stretching from
the halcyon days of helium-3 to the modern world of Majorana fermions. Along
the way, we will encounter such strange beasts as heavy fermion
superconductors, cuprates, and their iron-based cousins. Emphasis will be put
on the fact that in almo... | 1302.3176v2 |
2013-02-15 | PARSEC: A Parametrized Simulation Engine for Ultra-High Energy Cosmic Ray Protons | We present a new simulation engine for fast generation of ultra-high energy
cosmic ray data based on parametrizations of common assumptions of UHECR origin
and propagation. Implemented are deflections in unstructured turbulent
extragalactic fields, energy losses for protons due to photo-pion production
and electron-pai... | 1302.3761v2 |
2013-02-19 | Effect of magnetism on kinetics of "gamma"-"alpha" transformation and pattern formation in iron | Kinetics of polymorphous "gamma"-"alfa" transformation in Fe is studied
numerically within a model taking into account both lattice and magnetic
degrees of freedom, based on first-principle calculations of the total energy
for different magnetic states. It is shown that magnetoelastic phenomena,
namely, a strong sensit... | 1302.4643v2 |
2013-02-20 | Non-metallic, non-Fermi-liquid resistivity of FeCrAs from 0 to 17 GPa | An unusual, non-metallic resistivity of the 111 iron-pnictide compound FeCrAs
is shown to be relatively unchanged under pressures of up to 17 GPa. Combined
with our previous finding that this non-metallic behaviour persists from at
least 80 mK to 800 K, this shows that the non-metallic phase is exceptionally
robust. An... | 1302.4791v1 |
2013-02-20 | Transport signatures of spatially modulated electronic nematic phases | Electronic nematic phases are broadly characterized by spontaneously broken
rotational symmetry. Although they have been widely recognized in the context
of high temperature cuprates, bilayer ruthenates, and iron-based
superconductors, the focus so far has been exclusively on the uniform nematic
phase. Recently, howeve... | 1302.5117v1 |
2013-02-21 | Superconductivity induced by U-doping in the SmFeAsO system | Through partial substitution of Sm by U in SmFeAsO, a different member of the
family of iron-based superconductors was successfully synthesized. X-ray
diffraction measurements show that the lattice constants along the a and c axes
are both squeezed through U doping, indicating a successful substitution of U
at the Sm s... | 1302.5155v1 |
2013-02-28 | Synthesis of New Layered Oxypnictides Sr2CrO2(FeAs)2 | We successfully synthesized new layered iron oxypnictide Sr2CrO2(FeAs)2 by
solid-state-reaction techniques. This is the first report on the Fe-substituted
Sr2Mn3As2O2-type oxypnictides to our knowledge. A pellet of stoichiometric
mixtures of SrO, Cr and FeAs wrapped with tantalum foil was sintered at
900{\deg}C for 96 ... | 1302.7196v1 |
2013-03-01 | Expanded Iron UTA spectra -- probing the thermal stability limits in AGN clouds | The Fe unresolved transition array (UTAs) produce prominent features in the
15-17?A wavelength range in the spectra of Active Galactic Nuclei (AGN). Here
we present new calculations of the energies and oscillator strengths of inner-
shell lines from Fe XIV, Fe XV, and Fe XVI. These are crucial ions since they
are domin... | 1303.0316v1 |
2013-03-07 | Longitudinal magnetoresistance in Co-doped BaFe2As2 and LiFeAs single crystals: Interplay between spin fluctuations and charge transport in iron-pnictides | The longitudinal in-plane magnetoresistance (LMR) has been measured in
different Ba(Fe_(1-x)Co_x)2As2 single crystals and in LiFeAs. For all these
compounds, we find a negative LMR in the paramagnetic phase whose magnitude
increases as H^2. We show that this negative LMR can be readily explained in
terms of suppression... | 1303.1677v2 |
2013-03-07 | Studies of homogeneous precipitation in very dilute iron-coper alloys using kinetic Monte Carlo simulations and statistical theory of nucleation | Kinetics of homogeneous nucleation and growth of copper precipitates under
electron irradiation of Fe_{1-x}Cu_x alloys at concentrations x from 0.06 at.%
to 0.4 at.% and temperatures T from 290 to 450C is studied using the kinetic
Monte Carlo (KMC) simulations and the statistical theory of nucleation (STN).
The convent... | 1303.1753v1 |
2013-03-08 | Heat capacity jump at Tc and pressure derivatives of superconducting transition temperature in the Ba1-xKxFe2As2 (0.2 < x < 1.0) series | We present the evolution of the initial (up to ~ 10 kbar) hydrostatic,
pressure dependencies of Tc and of the ambient pressure jump in the heat
capacity associated with the superconducting transition as a function of K -
doping in the Ba1-xKxFe2As2 family of iron-based superconductors. The pressure
derivatives show wea... | 1303.2010v1 |
2013-03-11 | The Reach of INO for Atmospheric Neutrino Oscillation Parameters | The India-based Neutrino Observatory (INO) will host a 50 kt magnetized iron
calorimeter (ICAL@INO) for the study of atmospheric neutrinos. Using the
detector resolutions and efficiencies obtained by the INO collaboration from a
full-detector GEANT4-based simulation, we determine the reach of this
experiment for the me... | 1303.2534v2 |
2013-03-11 | Individual Alpha Elements, C, N, and Ba in Early Type Galaxies | Spectral data on early type galaxies is analyzed for chemical abundance with
an emphasis on obtaining detailed abundances for the elements O and Si in
addition to C, N, Na, Mg, Ca, Fe, and Ba. The abundance trends with velocity
dispersion fit preconceptions based upon previous Mg conclusions, namely that
larger galaxie... | 1303.2603v1 |
2013-03-13 | A Ni-Fe Layered Double Hydroxide-Carbon Nanotube Complex for Water Oxidation | Highly active, durable and cost-effective electrocatalysts for water
oxidation to evolve oxygen gas hold a key to a range of renewable energy
solutions including water splitting and rechargeable metal-air batteries. Here,
we report the synthesis of ultrathin nickel iron layered double hydroxide
nanoplates on mildly oxi... | 1303.3308v2 |
2013-03-14 | Quasiparticle mass enhancement close to the quantum critical point in BaFe$_2$(As$_{1-x}$P$_x$)$_2$ | We report a combined study of the specific heat and de Haas-van Alphen effect
in the iron-pnictide superconductor BaFe$_2$(As$_{1-x}$P$_x$)$_2$. Our data
when combined with results for the magnetic penetration depth give compelling
evidence for the existence of a quantum critical point (QCP) close to $x=0.30$
which aff... | 1303.3396v2 |
2013-03-14 | Investigation of charge states and multiferroicity in Fe-doped h-YMnO3 | Polycrystalline YMn1-xFexO3 (YMFO_x) (0 <= x <= 0.1) compounds have been
prepared in single phase and characterized by synchrotron X-ray diffraction,
X-ray absorption near edge spectroscopy, magnetization, and dielectric
measurements. Iron-substitution in hexagonal YMnO3 causes intra-lattice changes
exceeding those of ... | 1303.3398v2 |
2013-03-15 | Phase diagram and superconductivity at 58.1 K in α-FeAs free SmFeAsO1-xFx | The Phase diagram of SmFeAsO1-xFx in terms of x is exhibited in this study.
SmFeAsO1-xFx from x = 0 to x = 0.3 were prepared by low temperature sintering
with slow cooling. The low temperature sintering suppresses the formation of
the amorphous FeAs, which is inevitably produced as an impurity by using high
temperature... | 1303.3725v2 |
2013-03-17 | Two-dimensional magnetic interactions in LaFeAsO | Inelastic neutron scattering measurements demonstrate that the magnetic
interactions in antiferromagnetic LaFeAsO are two-dimensional. Spin wave
velocities within the Fe layer and the magnitude of the spin gap are similar to
the \textit{A}Fe$_2$As$_2$ based materials. However, the ratio of interlayer
and intralayer exc... | 1303.4033v1 |
2013-03-19 | <3D> NLTE line formation in the atmospheres of red supergiants | Red supergiants with their enormous brightness at J-band are ideal probes of
cosmic chemical composition. It is therefore crucial to have realistic models
of radiative transfer in their atmospheres, which will permit determination of
abundances accurate to 0.15 dex, the precision attainable with future telescope
facili... | 1303.4768v1 |
2013-03-24 | Determination of $sin^{2}θ_W$ using $ν(\barν)$-Nucleus scattering | We have studied nonisoscalarity and medium effects in the extraction of weak
mixing angle using Paschos and Wolfenstein relation in the iron nucleus.
Paschos and Wolfenstein(PW) relation is valid for an isoscalar target. We have
modified the PW relation for nonisoscalar target as well as incorporated the
medium effects... | 1303.5928v1 |
2013-03-29 | An analytically tractable model of bad metals | We discuss a model Kondo-type Hamiltonian representing an analytically
tractable version of the model used by Yin {\it et.al.}, Phys. Rev. B{\bf 86},
2399 (2012) to explain the non-Fermi liquid behavior of iron chalcogenides and
ruthenates in an intermediate energy range. We consider a regime where a
complete screening... | 1303.7448v2 |
2013-04-04 | On Euler's "Misleading Induction", Andrews' "Fix", and How to Fully Automate them | One of the greatest experimental mathematicians of all time was also one of
the greatest mathematicians of all time, the great Leonhard Euler. Usually he
had an uncanny intuition on how many "special cases" one needs before one can
formulate a plausible conjecture, but one time he was "almost fooled", only to
find out ... | 1304.1226v1 |
2013-04-04 | Ab-initio prediction of magnetoelectricity in infinite-layer CaFeO2 and MgFeO2 | Density functional based simulations are employed to explore magnetoelectric
effects in iron-based oxides, showing a unique layered structure. We
theoretically predict CaFeO2 to be a promising magnetoelectric, showing
magnetically-controlled large electric polarization, possibly even above room
temperature. The cross c... | 1304.1228v2 |
2013-04-04 | Revisiting the hardening of the cosmic-ray energy spectrum at TeV energies | Measurements of cosmic rays by experiments such as ATIC, CREAM, and PAMELA
indicate a hardening of the cosmic-ray energy spectrum at TeV energies. In our
recent work (Thoudam & H\"orandel 2012a), we showed that the hardening can be
due to the effect of nearby supernova remnants. We showed it for the case of
proton and ... | 1304.1400v2 |
2013-04-09 | Upper critical field of high quality single crystals of KFe$_2$As$_2$ | Measurements of temperature-dependent in-plane resistivity, $\rho(T)$, were
used to determine the upper critical field and its anisotropy in high quality
single crystals of stoichiometric iron arsenide superconductor KFe$_2$As$_2$.
The crystals were characterized by residual resistivity ratio,
$\rho(300K)/\rho(0)$ up t... | 1304.2689v1 |
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