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We reply to the recent Comment [<a href="https://arxiv.org/abs/cond-mat/9702231" data-arxiv-id="cond-mat/9702231" class="link-https">cond-mat/9702231</a>] by J. -M.
We report the results of a study of the magnetization losses in experimental multifilament, as well as control (uniform), coated superconductors exposed to time-varying magnetic field of various frequencies. Both the hysteresis loss, proportional to the sweep rate of the applied magnetic field, and the coupling loss, ...
We report new measurements on sup-gap energy structure originating from multiple Andreev reflections in mesoscopic SNS junctions. The junctions were fabricated in a planar geometry with high transparency superconducting contacts of Al deposited on highly diffusive and surface d-doped n++-GaAs.
The relationships among charge order, spin fluctuations, and superconductivity in underdoped cuprates remain controversial. We use neutron scattering techniques to study these phenomena in La$_{1.93}$Sr$_{0.07}$CuO$_4$, a superconductor with a transition temperature of $T_c = 20$~K.
There exists a large number of experimental and theoretical results supporting the picture of macroscopic qubits implemented by nanoscopic Josephson junctions of three different types -- charge qubit, flux qubit and phase qubit. The standard unified description of such systems is based on the formal quantization of th...
Phonon spectra have been investigated by micro-Raman scattering from 290 to 20K. New peaks at 500 and 674 cm-1 appear below 250K in MgB2.
The transport properties, upper critical fields, superconducting anisotropy, and critical current density in an iso-valent phosphorus-doped BaFe2As2 single crystal close to optimum doping are investigated in this report. Temperature dependent resistivity and susceptibility show a superconducting transition temperature...
It is widely perceived that the correlation effect may play an important role in several unconventional superconducting families, such as cuprate, iron-based and heavy-fermion superconductors. The application of high pressure can tune the ground state properties and balance the localization and itineracy of electrons ...
Electromagnetic responses in superconductors provide valuable information on the pairing symmetry as well as physical quantities such as the superfluid density. However, at the superconducting gap energy scale, optical excitations of the Bogoliugov quasiparticles are forbidden in conventional Bardeen-Cooper-Schrieffer...
Oxygen isotope (^{16}O/^{18}O) effects (OIE&#39;s) on the superconducting transition (T_c), the spin-glass ordering (T_g), and the antiferromagnetic ordering (T_N) temperatures were studied for Y_1-xPr_xBa_2Cu_3O_7-\delta as a function of Pr content (0.0\leq x \leq 1.0). The OIE on T_c increases with increasing x up t...
Consideration of the balance of forces on superconducting condensate at low frequencies leads to the well-known Josephson Relation. Using the Ginzburg-Landau expression for the current, an expression relating the electric field to the vortex velocity via the magnetic field is obtained.
In the recently discovered kagome superconductor AV3Sb5 (A = K, Rb, and Cs), the superconductivity is intertwined with an unconventional charge density wave order. Its pairing symmetry remains elusive owing to the lack of direct measurement of the superconducting gap in the momentum space.
We review electronic transport in superconducting junctions with Sr$_2$RuO$_4$. Transport measurements provide evidence for chiral domain walls and, therefore, chiral superconductivity in superconducting Sr$_2$RuO$_4$, but so far, the symmetry of the underlying superconducting state remains inconclusive.
Cobalt oxide superconductor NaxCoO2.yH2O is studied by angle-resolved photoemission spectroscopy (ARPES). We report the Fermi surface (FS) topology and electronic structure near the Fermi level (EF) of NaxCoO2.yH2O.
We study the thermal escape problem in the low damping limit. We find that finiteness of the barrier is crucial for explaining the thermal activation results.
We present a study of the topology of the normal state Fermi surface (FS) of the high Tc superconductor Bi2212 using angle-resolved photoemission. We present FS mapping experiments, recorded using unpolarised radiation with high (E,k) resolution, and an extremely dense sampling of k-space.
This is a response to the comment by J. Lidmar on our work in Phys. Rev. Lett.
Anisotropic properties of single crystals of SrPt$_{3}$P were studied using London penetration depth and electrical resistivity measurements. The upper critical field, $H_{c2}(T)$, was determined from four-probe electrical resistivity measurements for three orthogonal directions of a magnetic field with respect to the...
Experiments show that the Cooper pair transport in the insulator phase that forms at thin film superconductor to insulator transitions (SIT) is simply activated. This activated behavior depends on the microscopic factors that drive the localization of the Cooper pairs.
Diamond has always been adored as a jewel. Even more fascinating is its outstanding physical properties; it is the hardest material known in the world with the highest thermal conductivity.
We present the first infrared and optical study in the normal state of ab-plane oriented single crystals of the iron-oxypnictide superconductor LaFePO. We find that this material is a low carrier density metal with a moderate level of correlations and exhibits signatures of electron-boson coupling.
We report here the supplementary material for Ref. [1].
We have measured local structure of superconducting K_{0.8}Fe_{1.6}Se_{2} chalcogenide (T_{c}=31.8 K) by temperature dependent polarized extended x-ray absorption fine structure (EXAFS) at the Fe and Se K-edges. We find that the system is characterized by a large local disorder.
Superconductivity-induced changes of phonon lineshapes in niobium have been re-investigated by high-resolution inelastic neutron scattering. We show that the changes go beyond a simple change in lifetime and frequency when the phonon frequency is close to the superconducting energy gap $2\Delta$.
Mössbauer spectroscopy was used to probe the site specific information of the $K_{0.84}Fe_{1.99}Se_2$ superconductor. Possibility of coexistence of superconductivity and magnetism is discussed.
We uncover the low-energy spectrum of a t-J model for electrons on a square lattice of spin-1 iron atoms with 3dxz and 3dyz orbital character by applying Schwinger-boson-slave-fermion mean-field theory and by exact diagonalization of one hole roaming over a 4 x 4 x 2 lattice. Hopping matrix elements are set to produce...
FeSeTe has recently emerged as a leading candidate material for the two-dimensional topological superconductivity (TSC). Two reasons for the excitement are the high $T_c$ of the system and the fact that the Majorana zero modes (MZMs) inside the vortex cores live on the exposed surface rather than at the interface of a...
Understanding of unconventional superconductivity is crucial for engineering materials with specific order parameters or elevated superconducting transition temperatures. However, for many materials, the pairing mechanism and symmetry of the order parameter remain unclear: reliable and efficient methods of predicting ...
We investigate $T_c$ and magnetic penetration depth $\lambda (T)$ near the superconductor-metal quantum phase transition in overdoped $La_{2-x}Sr_{x}CuO_{4}$ films. Both $T_c$ and superfluid density $n_s$, $\propto \lambda^{-2}$, decrease with overdoping.
The vortex lattice with the superconducting and normal state charge carriers fractions may be regarded as three independent subsystems mutually connected by interactions. The equation of motion for these three subsystems must be solved simultaneously.
We synthesized the YBamCu1+mOy superconductors; m = 2,3,4,5 that were Y123 (YBa2Cu3O7-x), Y134 (YBa3Cu4O9-x), Y145 (YBa4Cu5O11-x), Y156 (YBa5Cu6O13-x), by solid state reaction with the Y2O3, BaCO3 and CuO as the beginning materials. The calcination temperature was 950 C and varied the sintering temperature to be 950 C...
A MgB2 superconducting tape has been successfully prepared by a new way of boron diffusion into Mg tape. This tape superconductor has a Tc of 39 K with a sharp transition width of 0.4 K, high bulk critical current density jc of 6.7*10^5 A/cm^2 in zero field at 6 K, higher irreversibility line comparing to that of a hi...
Resistive, magnetization, torque, specific heat and scanning tunneling microscopy measurements are carried out on the hole heavily doped CsFe$_2$As$_2$ single crystals. A characteristic temperature $T^*\sim13$ K, which is several times higher than the superconducting transition temperature $T_c=2.15$ K, is observed an...
Specific heats and transport quantities of the LaFe1-yNiyAsO0.89F0.11 system have been measured, and the results are discussed together with those reported previously by our group mainly for LaFe1-yCoyAsO0.89F0.11 and LaFeAsO0.89-xF0.11+x systems. The y dependence of the electronic specific heat coefficient gamma can ...
Superconductivity in strongly correlated systems is a remarkable phenomenon that attracts a huge interest. The study of this problem is relevant for materials as the high Tc oxides, pnictides and heavy fermions.
We report on isofield magnetic relaxation data on a single crystal of $Ba_{1-x}K_xFe_2As_2$ with superconducting transition temperature $T_c$= 32.7 K which exhibit the so called fish-tail effect. A surface map of the superconducting transition temperature shows that the superconducting properties are close to homogene...
Symmetry-breaking has been known to play a key role in noncentrosymmetric superconductors with strong spin-orbit-interaction (SOI). The studies, however, have been so far mainly focused on a particular type of SOI, known as Rashba SOI, whereby the electron spin is locked to its momentum at a right-angle, thereby leadi...
Energy applications employing high-temperature superconductors (HTS), such as motors/generators, transformers, transmission lines and fault current limiters, are usually operated in the alternate current (AC) regime. In order to be efficient, the HTS devices need to have a sufficiently low value of AC loss, in additio...
A model describing the Anderson impurity in the Bardeen-Cooper-Schriffer superconductor is proven to exhibit hidden integrability and is diagonalized exactly by the Bethe ansatz.
We study photon assisted tunneling in Nb/AlOx/Nb Josephson junctions. A quantitative calibration of the microwave field in the junction allowed direct verification of the quantum efficiency of microwave photon detection by the junctions.
We demonstrate full frequency conversion in the microwave domain using a Josephson three-wave mixing device pumped at the difference between the frequencies of its fundamental eigenmodes. By measuring the signal output as a function of the intensity and phase of the three input signal, idler and pump tones, we show th...
The Kagome material $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ ($A$ = K, Rb, Cs) with geometry frustration hosts non-trivial topological electronic structures, electronic nematicity, charge density wave (CDW) and superconductivity, providing an ideal platform to study the interplay between these phases. Specifically, in pressur...
We theoretically study the superconducting proximity effect in a quantum dot coupled to two superconducting leads when the intradot interaction between electrons is made attractive. Because of the superconducting proximity effect, the electronic states for the embedded quantum dot are either spin-polarized states with...
The influence of a partial substitution with sulphur into Te sites on the crystal, electronic and magnetic structures of FeTe is investigated by DFT calculations. The results reveal a phase transition from the antiferromagnetic double-stripe order for pure FeTe to the single-stripe order for S-substituted samples, whi...
We consider phase transitions and potential co-existence of spin-density-wave (SDW) magnetic order and extended s-wave ($s^+$) superconducting order within a two-band itinerant model of iron pnictides, in which SDW magnetism and $s^+$ superconductivity are competing orders. We show that depending on parameters, the tr...
We study exotic superconducting states in SrTiO$_3$ heterostructures on the basis of the three-orbital model, which reproduces the band structure of two-dimensional electron gases. We show various Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states induced by the broken inversion symmetry and orbital degree of freedom.
Motivated by the recent experimental realization of minimal Kitaev chains using quantum dots, we investigate the Majorana zero modes (MZM) in $Y$-shape Kitaev wires. We solve the associated Kitaev models analytically at the sweet spot ($t_h=\Delta$) and derive the exact form of MZM wave-functions in this geometry.
Trilayer La$_4$Ni$_3$O$_{10}$ has been recently found to exhibit superconductivity in its high-pressure phase, similar to the previously discovered bilayer La$_3$Ni$_2$O$_7$, but with a notably lower transition temperature. To date the pressure effects on the electronic correlations beneficial for unconventional super...
Dendritic flux avalanches is a frequently encountered consequence of the thermomagnetic instability in type-II superconducting films. The avalanches, potentially harmful for superconductor-based devices, can be suppressed by an adjacent normal metal layer, even when the two layers are not in thermal contact.
The ongoing quest for unambiguous signatures of topological superconductivity and Majorana modes in magnet-superconductor hybrid systems creates a high demand for suitable superconducting substrates. Materials that incorporate $s$-wave superconductivity with a wide energy gap, large spin-orbit coupling, and high surfa...
Physicists are searching for superconducting materials that can host Majoranas. New evidence for these elusive particles is provided by missing Shapiro steps in a Josephson effect mediated by an accidental Dirac semimetal.
Doped strontium titanate SrTiO$_3$ (STO) is one of the most dilute superconductors known today. The fact that superconductivity occurs at very low carrier concentrations is one of the two reasons that the pairing mechanism is not yet understood, the other is the role played by the proximity to a ferroelectric instabil...
The design and performance of the first vacuum ultra-violet (VUV) laser-based angle-resolved photoemission (ARPES) system are described. The VUV laser with a photon energy of 6.994 eV and bandwidth of 0.26 meV is achieved from the second harmonic generation using a novel non-linear optical crystal KBe2BO3F2 (KBBF).
We report the discovery of superconductivity in boron-doped diamond synthesized at high pressure (8-9 GPa) and temperature (2,500-2,800 K). Electrical resistivity, magnetic susceptibility, specific heat, and field-dependent resistance measurements show that boron-doped diamond is a bulk, type-II superconductor below t...
In Ref. [1], Minkov et al reported the time dependence of magnetic moment of hydride materials under high pressure in a diamond anvil cell.
We consider the simplest model for $T$ - linear growth of resistivity in metals. It is shown that the so called &#34;Planckian&#34; limit for the temperature dependent relaxation rate of electrons follows from a certain procedure for representation of experimental data on resistivity and, in this sense, is a kind of d...
Implanting fully polarized low energy muons on the nanometer scale beneath the surface of a superconductor in the Meissner state enabled us to probe the evanescent magnetic field profile B(z)(0&lt;z&lt;=200nm measured from the surface). All the investigated samples [Nb: kappa \simeq 0.7(2), Pb: kappa \simeq 0.6(1), Ta...
We investigated the Re-based kagome superconductor Re$_2$Zr through various measurements, including resistivity, magnetization, specific heat, and muon spin rotation and relaxation spectroscopy. These results suggest that Re$_2$Zr is a moderately coupled potential two-gap superconductor.
Improving the critical temperature (TC), critical magnetic field (HC), and critical current (JC) of superconducting materials has always been one of the most significant challenges in the field of superconductivity, but progress has been slow over the years. Based on the concept of injecting energy to enhance electron...
We have calculated the density of states $N(\omega)$ of a dirty but homogeneous superconductor in a high magnetic field. We assume a dilute concentration of scalar impurities and find how $N(\omega)$ behaves as one crosses from the weak scattering to the strong scattering limit.
The diamagnetism of a normal metal (N: Cu or Au), which is induced by the proximity effect of a superconductor (S: Nb), has been investigated for N-S double layers, which are formed by a thin-film deposition process. Detailed studies of samples, which have different electronic mean-free path \ell_N in N, suggest that ...
Superconductivity in flat-band systems, governed by quantum metric of Bloch states rather than the BCS framework, exhibits unique phenomena due to the vanishing electron group velocity. Here, we propose the vortex states and vortex size as direct probes to explore the quantum geometry effects in flat-band superconduct...
Spin-splitting induced in a conventional superconductor weakens superconductivity by destroying spin-singlet and creating spin-triplet Cooper pairs. We demonstrate theoretically that such an effect is also caused by an adjacent compensated antiferromagnet, which yields no net spin-splitting.
C$_3$N$_4$ is a recently discovered phase of carbon nitrides with the tetragonal crystal structure [<a href="http://D.Laniel" rel="external noopener nofollow" class="link-external link-http">this http URL</a> $\textit{et al. }$, Adv.
In high-Tc cuprate superconductors, violation of time-reversal symmetry (${\cal T}$) has been observed experimentally. In order to explain this phenomenon, we consider a flux phase in the t-J model.
I consider the problem of vortex tunneling in a two-dimensional superconductor. The vortex dynamics is governed by the Magnus force and the Ohmic friction force.
We present a comprehensive theory of light-controlled multi-band superconductivity and apply it to predict distinctive signatures of light-driven superconducting (SC) states in terahertz multi-dimensional coherent spectroscopy (THz-MDCS) experiments. We first derive gauge-invariant Maxwell-Bloch equations for multi-ba...
The interplay between quenched disorder and critical behavior in quantum phase transitions is conceptually fascinating and of fundamental importance for understanding phase transitions. However, it is still unclear whether or not the quenched disorder influences the universality class of quantum phase transitions.
We present fully self-consistent calculations of the thermodynamic properties of three-dimensional clean SNS Josephson junctions, where S is an s-wave short-coherence-length superconductor and N is a clean normal metal. The junction is modeled on an infinite cubic lattice such that the transverse width of the S is the...
The experimental critical temperatures and gap values of the superconducting pnictides of both the 1111 and 122 families can be simultaneously reproduced within the Eliashberg theory by using a three-band model where the dominant role is played by interband interactions and the order parameter undergoes a sigh reversal...
We present a detailed study of the electrical transport properties of YBa2Cu3O7-{\delta} thin film. The irreversibility fields ({\mu}_0 H_irr), upper critical fields ({\mu}_0 H_C2), penetration depths ({\lambda}) and coherence lengths ({\xi} ) of the YBa2Cu3O7-{\delta} materials are deduced from the resistivity curves...
Mass of Abrikosov vortices defied experimental observation for more than four decades. We demonstrate a method of its detection in high-temperature superconductors.
We study the vortex-dynamics of a BaFe{1.82}Ni_{0.18}As_2 crystal with Tc = 8 K, by measuring flux-creep over the second magnetisation (or fish-tail) peak for both H//c-axis and H//ab planes. Magnetic relaxation data show an anomalously long initial stage of relaxation, lasting approximately10 minutes for H//c-axis an...
Quantum nuclear effects and anharmonicity impact a wide range of functional materials and their properties. One of the most powerful techniques to model these effects is the Stochastic Self-Consistent Harmonic Approximation (SSCHA).
In disordered superconductors, the local pairing field fluctuates in space, leading to the smearing of the BCS peak in the density of states and appearance of the subgap tail states. We analyze the universal mesoscopic contributions to these effects and show that they are enhanced by the Coulomb repulsion.
We study the normal-state and superconducting properties of NaFe$_{1-x}$Co$_x$As system by specific heat measurements. Both the normal-state Sommerfeld coefficient and superconducting condensation energy are strongly suppressed in the underdoped and heavily overdoped samples.
The Ginzburg-Landau equations are solved for ideally periodic vortex lattices in superconducting films of arbitrary thickness in a perpendicular magnetic field. The order parameter, current density, magnetic moment, and the 3-dimensional magnetic field inside and outside the film are obtained in the entire ranges of t...
We study the synchronization in a one dimensional array of point Josephson junctions coupled to a common capacitor, which establishes a long-range interaction between junctions and synchronizes them. The stability diagram of synchronization in a noise-free system is obtained.
The spin valve effect for the superconducting current based on the superconductor/ferromagnet proximity effect has been studied for a CoO_x/Fe1/Cu/Fe2/Cu/Pb multilayer. The magnitude of the effect $\Delta T_c$ = T_c^{AP} - T_c^{P}, where T_c^{P} and T_c^{AP} are the superconducting transition temperatures for the para...
The superfluid transition in an ultracold two-component atomic Fermi gas is analyzed in the case where the two components have different densities. We describe a superfluid state which spontaneously breaks the rotational-symmetry by deforming the Fermi surfaces of both species into ellipsoidal form.
By using low-temperature scanning tunneling microscopy and spectroscopy (STM/STS), we observe in-gap states induced by Andreev tunneling through a single impurity state in a low carrier density superconductor (NaAlSi). The energy-symmetric in-gap states appear when the impurity state is located within the superconduct...
Here, we present the results of vibrating wire experiments in pure $^3$He (without $^4$He coverage) in nematic aerogel. We investigated the dependence of splitting of the superfluid transition temperature of $^3$He in aerogel on magnetic field.
Since its discovery, the superconducting phase in water-intercalated sodium cobaltates NaxCoO2 yH2O (x~0.3, y~1.3) has posed fundamental challenges in terms of experimental investigation and theoretical understanding. By a combined dynamical mean-field and renormalization group approach, we find an anisotropic chiral ...
We present the first comprehensive derivation of the intrinsic electronic phase diagram of the iron-oxypnictide superconductors in the normal state based on the analysis of the electrical resistivity $\rho$ of both LaFeAsO$_{1-x}$F$_x$ and SmFeAsO$_{1-x}$F$_x$ for a wide range of doping. Our data give clear-cut eviden...
A detailed study of the effect caused by the partial substitution of Ru by Ir on the magnetic and superconducting properties of the ruthenocuprate Ru(1-x)Ir(x)Sr2GdCu2o8; 0 &lt;= x &lt;= 0.10; is presented. The combined experimental results of structural, electrical, and magnetic measurements indicate that Ir substitu...
We grew the single crystals of the SnAs-based van der Waals (vdW)-type superconductor NaSn$_2$As$_2$ and systematically measured its resistivity, specific heat, and ultralow-temperature thermal conductivity. The superconducting transition temperature $T_c$ = 1.60 K of our single crystal is 0.3 K higher than that previ...
We investigate with a microscopic model anharmonic K-cation oscillation observed by neutron experiments in beta-pyrochlore superconductor KOs2O6, which also shows a mysterious first-order structural transition at Tp=7.5 K. We have identified a set of microscopic model parameters that successfully reproduce the observed...
The 2nd and 3rd order nonlinear microwave response of a superconducting YBa2Cu3O7 thin film resonator was synchronously measured using three input tones. This technique permits the local measurement, and hence mapping, of intermodulation distortion (IMD) inside the resonator.
We report 75As-NQR/NMR studies on the oxygen-deficient iron(Fe)-based oxypnictide superconductors LaFeAsO_{0.6} (T_c=28 K) along with the results on LaFeAsO, LaFeAsO_{0.75}(T_c=20 K) and NdFeAsO_{0.6}(T_c=53 K). Nuclear spin-lattice relaxation rate 1/T_1 of 75As NQR at zero field on LaFeAsO_{0.6} has revealed a T^3 de...
Recently, the search for Majorana fermions (MFs) has become one of the most important and exciting issues in condensed matter physics since such an exotic quasiparticle is expected to potentially give rise to unprecedented quantum phenomena whose functional properties will be used to develop future quantum technology. ...
Superconductor/ferromagnet bilayers are known to exhibit nontrivial dependence of the critical temperature T_c on the thickness d_f of the ferromagnetic layer. We develop a general method for investigation of T_c as a function of the bilayer&#39;s parameters.
We report on measurements of the in-plane magnetic penetration depth ($\lambda_{\rm ab}$) in single crystals of Sr$_2$RuO$_4$ down to $\simeq 0.015$ K by means of muon-spin rotation/relaxation. The linear temperature dependence of $\lambda^{-2}_{\rm ab}$ for $T\lesssim 0.7$ K suggests the presence of nodes in the supe...
We present here an overview of thermal conductivity behavior in magnetic superconductors: rare-earth nickel borocarbide intermetallic compounds, RNi_{2}B_{2}C, and the 2122 rare-earth rutheno-cuprates. The borocarbide family of intermetallics exhibits the large variety of phenomena - only superconductivity (R = Y, Lu)...
We have performed an angle-resolved photoemission spectroscopy (ARPES) study of the undoped and electron-doped iron pnictides BaFe2\_{-x}CoxAs2 (Ba122) (x=0, 0.14) and studied the Fermi surfaces (FSs) and band dispersions near the Fermi level. The FS sheets we observed are consistent with the shrinkage of the hole-lik...
We review the self-consistent mean-field theory for charge-frustrated Josephson junction arrays. Using &lt;cos(\phi)&gt; (\phi is the phase of the superconducting wavefunction) as order parameter and imposing the self-consistency condition, we compute the phase boundary line between the superconducting region (&lt;cos...
The surface impedance of Nb/CuMn (superconducting/spin-glass) bilayers has been measured at 10 GHz with the parallel plate resonator technique to obtain information about the exotic behavior of the order parameter in superconducting/magnetic proximity systems. The data strongly differs from the superconducting/normal-...
We show that the gauge field induced due to non-uniform hopping, in gapped graphene, can give rise to a non-BCS type of superconductivity. Unlike the conventional mechanisms, this superconductivity phenomena does not require any pairing.
The current-phase relation (CPR) for asymmetric 45 degree Josephson junctions between two d-wave superconductors has been predicted to exhibit an anomalous periodicity. We have used the single-junction interferometer to investigate the CPR for this kind of junctions in YBCO thin films.
We have performed thermal expansion and compressibility measurements on the recently discovered superconducting material NaxCoO2*4xD2O (x=1/3) using neutron powder diffraction over the temperature range 10-295 K and the pressure range 0-0.6 GPa. Pressure measurements were done in a helium-gas pressure cell.
The local density approximation is used to study the ground state superfluid properties of harmonically trapped p-wave Fermi gases as a function of fermion-fermion attraction strength. While the density distribution is bimodal on the weakly attracting BCS side, it becomes unimodal with increasing attraction and satura...