publicationDate
stringlengths
1
2.79k
title
stringlengths
1
36.5k
abstract
stringlengths
1
37.3k
id
stringlengths
9
47
2018-04-05
Stochastic ferrimagnetic Landau-Lifshitz-Bloch equation for finite magnetic structures
Precise modeling of the magnetization dynamics of nanoparticles with finite size effects at fast varying temperatures is a computationally challenging task. Based on the Landau-Lifshitz-Bloch (LLB) equation we derive a coarse grained model for disordered ferrimagnets, which is both fast and accurate. First, we incorpor...
1804.01724v1
2018-04-06
Temperature dependence of bulk viscosity within lattice simulation of $SU(3)$--gluodynamics
In this paper the temperature dependence of the $SU(3)$--gluodynamics bulk viscosity is studied within lattice simulations. To carry out this study we measure the correlation function of the trace of the energy-momentum tensor for a set of temperatures within the range $T/T_c \in (0.9, 1.5)$. To extract the bulk viscos...
1804.02382v2
2018-04-16
Anisotropy of exchange stiffness based on atomic-scale magnetic properties in rare-earth permanent magnet Nd$_2$Fe$_{14}$B
We examine the anisotropic properties of the exchange stiffness constant, $\mathcal{A}$, for rare-earth permanent magnet, Nd$_2$Fe$_{14}$B, by connecting analyses with two different scales of length, i.e., Monte Carlo (MC) method with an atomistic spin model and Landau-Lifshitz-Gilbert (LLG) equation with a continuous ...
1804.05824v2
2018-03-29
Percolative Mechanism of Aging in Zirconia-Containing Ceramics for Medical Applications
Recently, several episodes of fracture of zirconia ceramic femoral heads of total hip prostheses have alarmed the medical and scientific community regarding aging problems in zirconia prostheses. Such fractures cause immediate local tissue reactions, which require urgent medical intervention to prevent further complica...
1804.08696v1
2018-03-30
Reliability assessment in advanced nanocomposite materials for orthopaedic applications
Alumina-zirconia nano-composites were recently developed as alternative bearing materials for orthopedics. Previous, preliminary reports show that such alumina-zirconia nanocomposites exhibit high crack resistance and low wear rate. In this paper, additional information is given in terms of wear, crack resistance and a...
1804.08702v1
2018-04-26
Shape of a skyrmion
We propose a method of determining the shape of a two-dimensional magnetic skyrmion, which can be parameterized as the position dependence of the orientation of the local magnetic moment, by using the expansion in terms of the eigenfunctions of the Schr\"{o}dinger equation of a harmonic oscillator. A variational calcul...
1804.10162v3
2018-04-30
Modular Compact Modeling of Magnetic Tunnel Junction Devices
This paper describes a robust, modular, and physics- based circuit framework to model conventional and emerging Magnetic Tunnel Junction (MTJ) devices. Magnetization dynamics are described by the stochastic Landau-Lifshitz-Gilbert (sLLG) equation whose results are rigorously benchmarked with a Fokker-Planck Equation (F...
1805.00066v2
2018-05-22
Loss of Hall Conductivity Quantization in a Non-Hermitian Quantum Anomalous Hall Insulator
Recent work has extended topological band theory to open, non-Hermitian Hamiltonians, yet little is understood about how non-Hermiticity alters the topological quantization of associated observables. We address this problem by studying the quantum anomalous Hall effect (QAHE) generated in the Dirac surface states of a ...
1805.08892v2
2018-05-31
Spin-orbit torque induced dipole skyrmion motion at room temperature
We demonstrate deterministic control of dipole-field-stabilized skyrmions by means of spin-orbit torques arising from heavy transition-metal seed layers. Experiments are performed on amorphous Fe/Gd multilayers that are patterned into wires and exhibit stripe domains and dipole skyrmions at room temperature. We show th...
1805.12517v1
2018-06-11
Geometric Lagrangian averaged Euler-Boussinesq and primitive equations
In this article we derive the equations for a rotating stratified fluid governed by inviscid Euler-Boussinesq and primitive equations that account for the effects of the perturbations upon the mean. Our method is based on the concept of geometric generalized Lagrangian mean recently introduced by Gilbert and Vanneste, ...
1806.05053v2
2018-06-14
Topological quantization of the flow of magnetic skyrmions driven by a ratchet-like potential under thermal fluctuations
We consider a magnetic skyrmion adiabatically driven by a spin-polarized electrical current periodic in both space and time and asymmetric in space, and also subject to a random magnetic field representing the thermal fluctuations. We show that when the random magnetic field is low enough, while the time variation of t...
1806.05354v1
2018-06-17
Skyrmion Formation Induced by Antiferromagnetic-enhanced Interfacial Dzyaloshinskii Moriya Interaction
Ne\'el skyrmions originate from interfacial Dzyaloshinskii Moriya interaction (DMI). Recent studies have explored using ferromagnet to host Ne\'el skyrmions for device applications. However, challenges remain to reduce the size of skyrmion to near 10 nm. Amorphous rare-earth-transitional-metal ferrimagnets are attracti...
1806.06334v1
2018-06-17
Property Testing for Differential Privacy
We consider the problem of property testing for differential privacy: with black-box access to a purportedly private algorithm, can we verify its privacy guarantees? In particular, we show that any privacy guarantee that can be efficiently verified is also efficiently breakable in the sense that there exist two databas...
1806.06427v2
2018-06-25
Coupled Wire Models of Interacting Dirac Nodal Superconductors
Topological nodal superconductors possess gapless low energy excitations that are characterized by point or line nodal Fermi surfaces. In this work, using a coupled wire construction, we study topological nodal superconductors that have protected Dirac nodal points. In this construction, the low-energy electronic degre...
1806.09599v1
2018-07-02
A Broader View on Bias in Automated Decision-Making: Reflecting on Epistemology and Dynamics
Machine learning (ML) is increasingly deployed in real world contexts, supplying actionable insights and forming the basis of automated decision-making systems. While issues resulting from biases pre-existing in training data have been at the center of the fairness debate, these systems are also affected by technical a...
1807.00553v2
2018-07-06
Spin-torque-induced magnetization dynamics in ferrimagnets based on Landau-Lifshitz-Bloch Equation
A theoretical model based on the Landau-Lifshitz-Bloch equation is developed to study the spin-torque effect in ferrimagnets. Experimental findings, such as the temperature dependence, the peak in spin torque, and the angular-momentum compensation, can be well captured. In contrast to the ferromagnet system, the switch...
1807.02445v1
2018-07-10
Plumbing Constructions and the Domain of Outer Communication for 5-Dimensional Stationary Black Holes
The topology of the domain of outer communication for 5-dimensional stationary bi-axisymmetric black holes is classified in terms of disc bundles over the 2-sphere and plumbing constructions. In particular we find an algorithmic bijective correspondence between the plumbing of disc bundles and the rod structure formali...
1807.03452v1
2018-07-13
Deep Learning in the Wild
Deep learning with neural networks is applied by an increasing number of people outside of classic research environments, due to the vast success of the methodology on a wide range of machine perception tasks. While this interest is fueled by beautiful success stories, practical work in deep learning on novel tasks wit...
1807.04950v1
2018-07-16
Digital frequency multiplexing with sub-Kelvin SQUIDs
Digital frequency multiplexing (dfMux) is a readout architecture for transition edge sensor-based detector arrays and is used on telescopes including SPT-3G, POLARBEAR-2, and LiteBIRD. Here, we present recent progress and plans for development of a sub-Kelvin SQUID architecture for digital frequency multiplexed bolomet...
1807.05995v1
2018-07-20
Sphinx: a massively multiplexed fiber positioner for MSE
In this paper we present the Australian Astronomical Observatory's concept design for Sphinx - a fiber positioned with 4332 spines on a 7.77mm pitch for CFHT's Mauna Kea Spectroscopic Explorer (MSE) Telescope. Based on the Echidna technology used with FMOS (on Subaru) and 4MOST (on VISTA), the next evolution of the til...
1807.09181v1
2018-07-30
Graphs admitting only constant splines
We study {\em generalized graph splines,} introduced by Gilbert, Viel, and the last author. For a large class of rings, we characterize the graphs that only admit constant splines. To do this, we prove that if a graph has a particular type of cutset (e.g., a bridge), then the space of splines naturally decomposes as a ...
1807.11515v2
2018-08-05
Searching for patchy reionization from cosmic microwave background with hybrid quadratic estimators
We propose a hybrid quadratic estimator to measure cross correlations between gravitational lensing of the cosmic microwave background (CMB) and differential screening effects arising from fluctuations in the electron column density, such as could arise from patchy reionization. The hybrid quadratic estimators are vali...
1808.01592v1
2018-08-08
Revisiting Gilbert Strang's "A Chaotic Search for $i$"
In the paper "A Chaotic Search for $i$"~(\cite{strang1991chaotic}), Strang completely explained the behaviour of Newton's method when using real initial guesses on $f(x) = x^{2}+1$, which has only a pair of complex roots $\pm i$. He explored an exact symbolic formula for the iteration, namely $x_{n}=\cot{ \left( 2^{n} ...
1808.03229v1
2018-08-11
Micromagnetic modeling of Terahertz oscillations in an antiferromagnetic material driven by spin-Hall effect
The realization of THz sources is a fundamental aspect for a wide range of applications. Over different approaches, compact THz oscillators can be realized taking advantage of dynamics in antiferromagnetic (AFMs) thin films driven by spin-Hall effect. Here we perform a systematic study of these THz oscillators within a...
1808.03773v1
2018-08-30
Iterative solution and preconditioning for the tangent plane scheme in computational micromagnetics
The tangent plane scheme is a time-marching scheme for the numerical solution of the nonlinear parabolic Landau-Lifshitz-Gilbert equation (LLG), which describes the time evolution of ferromagnetic configurations. Exploiting the geometric structure of LLG, the tangent plane scheme requires only the solution of one linea...
1808.10281v1
2018-09-12
Iterative Delegations in Liquid Democracy with Restricted Preferences
In this paper, we study liquid democracy, a collective decision making paradigm which lies between direct and representative democracy. One main feature of liquid democracy is that voters can delegate their votes in a transitive manner so that: A delegates to B and B delegates to C leads to A delegates to C. Unfortunat...
1809.04362v2
2018-09-25
Phase change materials for nano-polaritonics: a case study of hBN/VO2 heterostructures
Polaritonic excitation and control in van der Waals (vdW) materials exhibit superior merits than conventional materials and thus hold new promise for exploring light matter interactions. In this work, we created vdW heterostructures combining hexagonal boron nitride (hBN) and a representative phase change material - va...
1809.09652v1
2018-10-08
Causal isotonic regression
In observational studies, potential confounders may distort the causal relationship between an exposure and an outcome. However, under some conditions, a causal dose-response curve can be recovered using the G-computation formula. Most classical methods for estimating such curves when the exposure is continuous rely on...
1810.03269v2
2018-10-10
On the Approximation Properties of Random ReLU Features
We study the approximation properties of random ReLU features through their reproducing kernel Hilbert space (RKHS). We first prove a universality theorem for the RKHS induced by random features whose feature maps are of the form of nodes in neural networks. The universality result implies that the random ReLU features...
1810.04374v3
2018-10-15
ABACUS: Unsupervised Multivariate Change Detection via Bayesian Source Separation
Change detection involves segmenting sequential data such that observations in the same segment share some desired properties. Multivariate change detection continues to be a challenging problem due to the variety of ways change points can be correlated across channels and the potentially poor signal-to-noise ratio on ...
1810.06167v1
2018-10-24
Photoinduced topological spin texture in a metallic ferromagnet
Photoinduced nonequilibrium spin structure is examined in the double-exchange model, in which itinerant electrons couple with localized spins through the ferromagnetic Hund coupling. In particular, we focus on the transient spin structure from the initial ferromagnetic metallic state to the steady antiferromagnetic ord...
1810.10244v1
2018-11-01
Time Quantified Monte Carlo Method for Long-range Interacting Systems
We propose a method for simulating the stochastic dynamics of classical spin systems with long-range interactions. The method incorporates the stochastic cutoff (SCO) method, which is originally specialized for simulating equilibrium state, into time quantified Monte Carlo (TQMC) method. We analytically prove that the ...
1811.00237v2
2018-11-01
Spatial Functional Linear Model and its Estimation Method
The classical functional linear regression model (FLM) and its extensions, which are based on the assumption that all individuals are mutually independent, have been well studied and are used by many researchers. This independence assumption is sometimes violated in practice, especially when data with a network structu...
1811.00314v1
2018-11-12
New Theoretical Bounds and Constructions of Permutation Codes under Block Permutation Metric
Permutation codes under different metrics have been extensively studied due to their potentials in various applications. Generalized Cayley metric is introduced to correct generalized transposition errors, including previously studied metrics such as Kendall's $\tau$-metric, Ulam metric and Cayley metric as special cas...
1811.04600v1
2018-11-13
Classical Access Structures of Ramp Secret Sharing Based on Quantum Stabilizer Codes
In this paper we consider to use the quantum stabilizer codes as secret sharing schemes for classical secrets. We give necessary and sufficient conditions for qualified and forbidden sets in terms of quantum stabilizers. Then we give a Gilbert-Varshamove-type sufficient condition for existence of secret sharing schemes...
1811.05217v7
2018-11-13
Enhanced domain wall velocity near a ferromagnetic instability
Assuming a Fermi liquid behavior for $s$-conduction electrons, we rewrite the extended Landau-Lifshitz-Gilbert (LLG) equation renormalized by interactions through the Landau parameters $F^{a}_{l}$ ($l=0,1,2 \cdots$) in an explicit form to describe the dynamic of a domain wall (DW) due to spin transfer torque phenomenon...
1811.05380v4
2018-12-07
Coding over Sets for DNA Storage
In this paper we study error-correcting codes for the storage of data in synthetic deoxyribonucleic acid (DNA). We investigate a storage model where a data set is represented by an unordered set of $M$ sequences, each of length $L$. Errors within that model are a loss of whole sequences and point errors inside the sequ...
1812.02936v3
2018-12-14
Computational micromagnetics with Commics
We present our open-source Python module Commics for the study of the magnetization dynamics in ferromagnetic materials via micromagnetic simulations. It implements state-of-the-art unconditionally convergent finite element methods for the numerical integration of the Landau-Lifshitz-Gilbert equation. The implementatio...
1812.05931v1
2019-01-10
Multi-Parameter Regression Survival Modelling: An Alternative to Proportional Hazards
It is standard practice for covariates to enter a parametric model through a single distributional parameter of interest, for example, the scale parameter in many standard survival models. Indeed, the well-known proportional hazards model is of this kind. In this paper we discuss a more general approach whereby covaria...
1901.03277v1
2019-02-01
A Penrose-Type Inequality with Angular Momentum and Charge for Axisymmetric Initial Data
A lower bound for the ADM mass is established in terms of angular momentum, charge, and horizon area in the context of maximal, axisymmetric initial data for the Einstein-Maxwell equations which satisfy the weak energy condition. If, on the horizon, the given data agree to a certain extent with the associated model Ker...
1902.00501v3
2019-02-08
Field-tuned spin excitation spectrum of $kπ$-skyrmion
We study spin-wave excitation modes of $k\pi$ skyrmion in a magnetic nanodot under an external magnetic field along $z$-direction using micromagnetic simulations based on Landau-Lifshitz-Gilbert equation. We find that a transition of $k\pi$ skyrmion to other skyrmion-like structures appears under some critical external...
1902.02901v2
2019-02-08
Simulation of the Magnetization Dynamics of a Single Domain BiFeO$_3$ Thin Film
The switching dynamics of a single-domain BiFeO$_3$ thin films is investigated through combining the dynamics of polarization and Neel vector. The evolution of the ferroelectric polarization is described by the Landau-Khalatnikov (LK) equation, and the Landau-Lifshitz-Gilbert (LLG) equations for spins in two sublattice...
1902.03330v1
2019-02-13
Dynamics of ferromagnetic domain walls under extreme fields
We report the existence of a new regime for domain wall motion in uniaxial and near-uniaxial ferromagnetic nanowires, characterised by applied magnetic fields sufficiently strong that one of the domains becomes unstable. There appears a new stable solution of the Landau-Lifshitz-Gilbert equation, describing a nonplanar...
1902.04968v3
2019-02-28
Topological $d$-wave Superconductivity and Nodal Line-Arc Intersections in Weyl Semimetals
Superconducting Weyl semimetals present a novel and promising system to harbor new forms of unconventional topological superconductivity. Within the context of time-reversal symmetric Weyl semimetals with $d$-wave superconductivity, we demonstrate that the number of Majorana cones equates to the number of intersections...
1903.00024v2
2019-03-07
Stronger L2/L2 Compressed Sensing; Without Iterating
We consider the extensively studied problem of $\ell_2/\ell_2$ compressed sensing. The main contribution of our work is an improvement over [Gilbert, Li, Porat and Strauss, STOC 2010] with faster decoding time and significantly smaller column sparsity, answering two open questions of the aforementioned work. Previous...
1903.02742v1
2019-03-17
A Brief history of mangnetism
In this article an overview of the historical development of the key ideas in the field of magnetism is presented. The presentation is semi-technical in nature.Starting by noting down important contribution of Greeks, William Gilbert, Coulomb, Poisson, Oersted, Ampere, Faraday, Maxwell, and Pierre Curie, we review earl...
1903.07031v1
2019-03-19
Separability Properties of Nilpotent $\mathbb{Q}[x]$-Powered Groups
In this paper we study conjugacy and subgroup separability properties in the class of nilpotent $\mathbb{Q}[x]$-powered groups. Many of the techniques used to study these properties in the context of ordinary nilpotent groups carry over naturally to this more general class. Among other results, we offer a generalizatio...
1903.08220v1
2019-03-24
Synchronized, periodic, and chaotic dynamics in spin torque oscillator with two free layers
A phase diagram of the magnetization dynamics is studied by numerically solving the Landau-Lifshitz-Gilbert (LLG) equation in a spin torque oscillator consisting of asymmetric two free layers that are magnetized in in-plane direction. We calculated the dynamics for a wide range of current density for both low and high ...
1903.09938v2
2019-04-07
Hybrid Approaches to Detect Comments Violating Macro Norms on Reddit
In this dataset paper, we present a three-stage process to collect Reddit comments that are removed comments by moderators of several subreddits, for violating subreddit rules and guidelines. Other than the fact that these comments were flagged by moderators for violating community norms, we do not have any other infor...
1904.03596v2
2019-04-11
Triangular array of iron-oxide nanoparticles: A simulation study of intra- and inter-particle magnetism
A study of spherical maghemite nanoparticles on a two dimensional triangular array was carried out using a stochastic Landau-Lifshitz-Gilbert (sLLG) approach. The simulation method was first validated with a triangular array of simple dipoles, where results show the expected phase transition to a ferromagnetic state at...
1904.05515v1
2019-04-15
Mathematical analysis of weak and strong solutions to an evolutionary model for magnetoviscoelasticity
The paper is concerned with the analysis of an evolutionary model for magnetoviscoelastic materials in two dimensions. The model consists of a Navier-Stokes system featuring a dependence of the stress tensor on elastic and magnetic terms, a regularized system for the evolution of the deformation gradient and the Landau...
1904.07179v1
2019-04-25
Message Randomization and Strong Security in Quantum Stabilizer-Based Secret Sharing for Classical Secrets
We improve the flexibility in designing access structures of quantum stabilizer-based secret sharing schemes for classical secrets, by introducing message randomization in their encoding procedures. We generalize the Gilbert-Varshamov bound for deterministic encoding to randomized encoding of classical secrets. We also...
1904.11114v3
2019-05-02
Benchmark Instances and Branch-and-Cut Algorithm for the Hashiwokakero Puzzle
Hashiwokakero, or simply Hashi, is a Japanese single-player puzzle played on a rectangular grid with no standard size. Some cells of the grid contain a circle, called island, with a number inside it ranging from one to eight. The remaining positions of the grid are empty. The player must connect all of the islands by d...
1905.00973v1
2019-05-06
An excess of non-Gaussian fluctuations in the cosmic infrared background consistent with gravitational lensing
The cosmic infrared background (CIB) is gravitationally lensed. A quadratic-estimator technique that is inherited from lensing analyses of the cosmic microwave background (CMB) can be applied to detect the CIB lensing effects. However, the CIB fluctuations are intrinsically strongly non-Gaussian, making CIB lensing rec...
1905.02084v1
2019-05-14
Multi-reference quantum chemistry protocol for simulating autoionization spectra: Test of ionization continuum models for the neon atom
In this contribution we present a protocol to evaluate partial and total Auger decay rates combining the restricted active space self-consistent field electronic structure method for the bound part of the spectrum and numerically obtained continuum orbitals in the single-channel scattering theory framework. On top of t...
1905.05785v2
2019-06-16
A concise guide to existing and emerging vehicle routing problem variants
Vehicle routing problems have been the focus of extensive research over the past sixty years, driven by their economic importance and their theoretical interest. The diversity of applications has motivated the study of a myriad of problem variants with different attributes. In this article, we provide a concise overvie...
1906.06750v2
2019-07-01
Formation process of skyrmion lattice domain boundaries: The role of grain boundaries
We report on the formation process of skyrmion lattice (SkL) domain boundaries in FeGe using Lorentz transmission electron microscopy and small-angle electron diffraction. We observed that grain boundaries and edges play an important role in the formation of SkL domain boundaries; The SkL domain boundary is stabilized ...
1907.00774v1
2019-07-02
Quantum Data-Syndrome Codes
Performing active quantum error correction to protect fragile quantum states highly depends on the correctness of error information--error syndromes. To obtain reliable error syndromes using imperfect physical circuits, we propose the idea of quantum data-syndrome (DS) codes that are capable of correcting both data qub...
1907.01393v1
2019-07-02
Prediction of topological Hall effect in a driven magnetic domain wall
We investigate the possible emergence of topological Hall effect (THE) in a driven magnetic DW. Numerical simulation based on the Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation shows that the emergent magnetic flux appears when the DW is in a non-equilibrium state. The magnitude of magnetic flux is modulated by Dz...
1907.01648v2
2019-07-04
Resonant Acoustic Wave Assisted Spin-Transfer-Torque Switching of Nanomagnets
We report the possibility of achieving an order of magnitude reduction in the energy dissipation needed to write bits in perpendicular magnetic tunnel junctions (p-MTJs) by simulating the magnetization dynamics under a combination of resonant surface acoustic waves (r-SAW) and spin-transfer-torque (STT). The magnetizat...
1907.02255v1
2019-07-04
Second-order semi-implicit projection methods for micromagnetics simulations
Micromagnetics simulations require accurate approximation of the magnetization dynamics described by the Landau-Lifshitz-Gilbert equation, which is nonlinear, nonlocal, and has a non-convex constraint, posing interesting challenges in developing numerical methods. In this paper, we propose two second-order semi-implici...
1907.02358v1
2019-07-11
Astro2020 Activity, Project of State of the Profession Consideration (APC) White Paper: All-Sky Near Infrared Space Astrometry. State of the Profession Considerations: Development of Scanning NIR Detectors for Astronomy
Gaia is a revolutionary space mission developed by ESA and is delivering 5 parameter astrometry, photometry and radial velocities over the whole sky with astrometric accuracies down to a few tens of micro-arcseconds. A weakness of Gaia is that it only operates at optical wavelengths. However, much of the Galactic centr...
1907.05191v1
2019-07-21
Performance of a low-parasitic frequency-domain multiplexing readout
Frequency-domain multiplexing is a readout technique for transition edge sensor bolometer arrays used on modern CMB experiments, including the SPT-3G receiver. Here, we present design details and performance measurements for a low-parasitic frequency-domain multiplexing readout. Reducing the parasitic impedance of the ...
1907.09035v1
2019-08-09
MakeSense: An IoT Testbed for Social Research of Indoor Activities
There has been increasing interest in deploying IoT devices to study human behaviour in locations such as homes and offices. Such devices can be deployed in a laboratory or `in the wild' in natural environments. The latter allows one to collect behavioural data that is not contaminated by the artificiality of a laborat...
1908.03380v1
2019-08-13
On Steane-Enlargement of Quantum Codes from Cartesian Product Point Sets
In this work, we study quantum error-correcting codes obtained by using Steane-enlargement. We apply this technique to certain codes defined from Cartesian products previously considered by Galindo et al. in [4]. We give bounds on the dimension increase obtained via enlargement, and additionally give an algorithm to co...
1908.04560v1
2019-08-17
Band-pass Magnetic Tunnel Junction based Magnetoresistive Random Access Memory
We propose spin transfer torque--magnetoresistive random access memory (STT-MRAM) based on magneto-resistance and spin transfer torque physics of band-pass spin filtering. Utilizing the electronic analogs of optical phenomena such as anti-reflection coating and resonance for spintronic devices, we present the design of...
1908.06279v1
2019-09-09
Narrow autoresonant magnetization structures in finite length ferromagnetic nanoparticles
The autoresonant approach to excitation and control of large amplitude uniformly precessing magnetization structures in finite length easy axis ferromagnetic nanoparticles is suggested and analyzed within the Landau-Lifshitz-Gilbert model. These structures are excited by using a spatially uniform, oscillating, chirped ...
1909.03671v1
2019-09-09
Reliability and Error Burst Length Analysis of Wireless Multi-Connectivity
Multi-connectivity offers diversity in terms of multiple interfaces through which the data can be sent, thereby improving simultaneously the overall reliability and latency. This makes interface diversity a natural candidate for supporting Ultra-Reliable Low Latency Communications (URLLC). This work investigates how th...
1909.03875v1
2019-09-13
Hidden spin-orbital order in the Kitaev hyperhoneycomb $β$-Li$_2$IrO$_3$
We report the existence of a phase transition at high temperature in the 3D Kitaev candidate material, $\beta$-Li$_2$IrO$_3$. We show that the transition is bulk, intrinsic and orders a tiny magnetic moment with a spatially anisotropic saturation moment. We show that even though this transition is global, it does not f...
1909.06355v1
2019-10-08
Gravitational Lensing of the Cosmic Neutrino Background
We study gravitational lensing of the cosmic neutrino background. This signal is undetectable for the foreseeable future, but there is a rich trove of information available. At least some of the neutrinos from the early universe will be non-relativistic today, with a closer surface of last scattering (compared to the c...
1910.03550v3
2019-10-17
A multi-scale approach for magnetisation dynamics: Unraveling exotic magnetic states of matter
Crystallographic lattice defects strongly influence dynamical properties of magnetic materials at both microscopic and macroscopic length scales. A multi-scale approach to magnetisation dynamics, which is presented in this paper, accurately captures such effects. The method is illustrated using examples of systems with...
1910.07807v1
2019-10-21
Generation of exchange magnons in thin ferromagnetic films by ultrashort acoustic pulses
We investigate generation of exchange magnons by ultrashort, picosecond acoustic pulses propagating through ferromagnetic thin films. Using the Landau-Lifshitz-Gilbert equations we derive the dispersion relation for exchange magnons for an external magnetic field tilted with respect to the film normal. Decomposing the ...
1910.09481v1
2019-11-05
Numerical methods for antiferromagnetics
Compared with ferromagnetic counterparts, antiferromagnetic materials are considered as the future of spintronic applications since these materials are robust against the magnetic perturbation, produce no stray field, and display ultrafast dynamics. There are (at least) two sets of magnetic moments in antiferromagnets ...
1911.01717v1
2019-11-08
A filamentary cascade model of the inertial range
This paper develops a simple model of the inertial range of turbulent flow, based on a cascade of vortical filaments. A binary branching structure is proposed, involving the splitting of filaments at each step into pairs of daughter filaments with differing properties, in effect two distinct simultaneous cascades. Neit...
1911.03537v2
2019-11-14
Beyond Pairwise Comparisons in Social Choice: A Setwise Kemeny Aggregation Problem
In this paper, we advocate the use of setwise contests for aggregating a set of input rankings into an output ranking. We propose a generalization of the Kemeny rule where one minimizes the number of k-wise disagreements instead of pairwise disagreements (one counts 1 disagreement each time the top choice in a subset o...
1911.06226v2
2019-11-15
A geometric look at momentum flux and stress in fluid mechanics
We develop a geometric formulation of fluid dynamics, valid on arbitrary Riemannian manifolds, that regards the momentum-flux and stress tensors as 1-form valued 2-forms, and their divergence as a covariant exterior derivative. We review the necessary tools of differential geometry and obtain the corresponding coordina...
1911.06613v2
2019-11-18
Theoretical condition for switching the magnetization in a perpendicularly magnetized ferromagnet via the spin Hall effect
A theoretical formula is derived for the threshold current to switch a perpendicular magnetization in a ferromagnet by the spin Hall effect. The numerical simulation of the Landau-Lifshitz-Gilbert equation indicates that magnetization switching is achieved when the steady-state solution of the magnetization in the pres...
1911.07961v1
2019-12-11
Constructions of quasi-twisted quantum codes
In this work, our main objective is to construct quantum codes from quasi-twisted (QT) codes. At first, a necessary and sufficient condition for Hermitian self-orthogonality of QT codes is introduced by virtue of the Chinese Remainder Theorem (CRT). Then we utilize these self-orthogonal QT codes to provide quantum code...
1912.05142v2
2019-12-12
The strange metal Hall effect connects quantum criticality and superconductivity in an iron-based superconductor
Many unconventional superconductors exhibit a common set of anomalous charge transport properties that characterize them as `strange metals', which provides hope that there is single theory that describes them. However, model-independent connections between the strange metal and superconductivity have remained elusive....
1912.06130v1
2019-12-17
SINR percolation for Cox point processes with random powers
Signal-to-interference plus noise ratio (SINR) percolation is an infinite-range dependent variant of continuum percolation modeling connections in a telecommunication network. Unlike in earlier works, in the present paper the transmitted signal powers of the devices of the network are assumed random, i.i.d. and possibl...
1912.07895v2
2019-12-18
Magnetic hysteresis behavior of granular manganite La$_{0.67}$Ca$_{0.33}$MnO$_3$ nanotubes
A silicon micromechanical torsional oscillator is used to measure the hysteresis loops of two manganite La_0.67Ca_0.33MnO_3 nanotubes at different temperatures, applying an external field along its main axes. These structures are composed of nanograins with a ferromagnetic core surrounded by a dead layer. Micromagnetic...
1912.08844v2
2019-12-30
Distribution of the minimal distance of random linear codes
In this paper, we study the distribution of the minimal distance (in the Hamming metric) of a random linear code of dimension $k$ in $\mathbb{F}_q^n$. We provide quantitative estimates showing that the distribution function of the minimal distance is close ({\it{}superpolynomially} in $n$)to the cumulative distribution...
1912.12833v2
2020-01-12
Magnetic Skyrmions in FePt Square-Based Nanoparticles Around Room-Temperature
Magnetic skyrmions formed at temperatures around room temperature in square-based parallelepiped magnetic FePt nanoparticles with perpendicular magnetocrystalline anisotropy (MCA) were studied during the magnetization reversal using micromagnetic simulations. Finite Differences (FD) method were used for the solution of...
2001.03902v3
2020-01-20
Investigation of Patient-sharing Networks Using a Bayesian Network Model Selection Approach for Congruence Class Models
A Bayesian approach to conduct network model selection is presented for a general class of network models referred to as the congruence class models (CCMs). CCMs form a broad class that includes as special cases several common network models, such as the Erd\H{o}s-R\'{e}nyi-Gilbert model, stochastic block model and man...
2001.06974v1
2020-02-11
Fidimag -- a finite difference atomistic and micromagnetic simulation package
Fidimag is an open-source scientific code for the study of magnetic materials at the nano- or micro-scale using either atomistic or finite difference micromagnetic simulations, which are based on solving the Landau-Lifshitz-Gilbert equation. In addition, it implements simple procedures for calculating energy barriers i...
2002.04318v1
2020-01-13
Malware propagation in urban D2D networks
We introduce and analyze models for the propagation of malware in pure D2D networks given via stationary Cox-Gilbert graphs. Here, the devices form a Poisson point process with random intensity measure $\lambda\Lambda$, where $\Lambda$ is stationary and given, for example, by the edge-length measure of a realization of...
2002.06248v1
2020-02-17
How fast can you update your MST? (Dynamic algorithms for cluster computing)
Imagine a large graph that is being processed by a cluster of computers, e.g., described by the $k$-machine model or the Massively Parallel Computation Model. The graph, however, is not static; instead it is receiving a constant stream of updates. How fast can the cluster process the stream of updates? The fundamental ...
2002.06762v1
2020-02-22
Bose-Einstein Condensation of Nonequilibrium Magnons in Confined Systems
We study the formation of a room temperature magnon Bose-Einstein condensate (BEC) in nanoscopic systems and demonstrate that its lifetime is influenced by the spatial confinement. We predict how dipolar interactions and nonlinear magnon scattering assist in the generation of a metastable magnon BEC in energy-quantized...
2002.09777v2
2020-02-25
Bias-field-free spin Hall nano-oscillators with an out-of-plane precession mode
Spin Hall nano-oscillators (SHNOs) are promising candidates for new microwave oscillators with high durability due to a small driving current. However, conventional SHNOs with an in-plane precession (IPP) mode require a bias field for stable oscillations which is not favored in certain applications such as neuromorphic...
2002.10753v1
2020-03-06
Spin-accumulation induced magnetic texture in a metal-insulator bilayer
We consider the influence of a spin accumulation in a normal metal on the magnetic statics and dynamics in an adjacent magnetic insulator. In particular, we focus on arbitary angles between the spin accumulation and the easy-axis of the magnetic insulator. Based on Landau-Lifshitz-Gilbert phenomenology supplemented wit...
2003.03226v1
2020-04-05
Domain wall diode based on functionally graded Dzyaloshinskii-Moriya interaction
We present a general approach for studying the dynamics of domain walls in biaxial ferromagnetic stripes with functionally graded Dzyaloshinskii-Moriya interaction (DMI). By engineering the spatial profile of the DMI parameter we propose the concept of a diode, which implements filtering of domain walls of certain topo...
2004.02175v1
2020-05-03
Philosophy-Guided Mathematical Formalism for Complex Systems Modelling
We recently presented the so-called allagmatic method, which includes a system metamodel providing a framework for describing, modelling, simulating, and interpreting complex systems. Its development and programming was guided by philosophy, especially by Gilbert Simondon's philosophy of individuation, Alfred North Whi...
2005.01192v5
2020-05-07
A closer look at the non-Hopfianness of $BS(2,3)$
The Baumslag-Solitar group $BS(2,3)$, is a so-called non-Hopfian group, meaning that it has an epimorphism $\phi$ onto itself, that is not injective. In particular this is equivalent to saying that $BS(2,3)$ has a non-trivial quotient that is isomorphic to itself. As a consequence the Cayley graph of $BS(2,3)$ has a qu...
2005.03396v2
2020-05-08
Project and Forget: Solving Large-Scale Metric Constrained Problems
Given a set of dissimilarity measurements amongst data points, determining what metric representation is most "consistent" with the input measurements or the metric that best captures the relevant geometric features of the data is a key step in many machine learning algorithms. Existing methods are restricted to specif...
2005.03853v2
2020-05-27
The Kirillov model in families
Let $F$ be a non-archimedean local field, let $k$ be an algebraically closed field of characteristic $\ell$ different from the residual characteristic of $F$, and let $A$ be a commutative Noetherian $W(k)$-algebra, where $W(k)$ denotes the Witt vectors. Using the Rankin-Selberg functional equations and extending recent...
2005.13484v3
2020-05-29
An Explicit Formula for the Zero-Error Feedback Capacity of a Class of Finite-State Additive Noise Channels
It is known that for a discrete channel with correlated additive noise, the ordinary capacity with or without feedback both equal $ \log q-\mathcal{H} (Z) $, where $ \mathcal{H}(Z) $ is the entropy rate of the noise process $ Z $ and $ q $ is the alphabet size. In this paper, a class of finite-state additive noise chan...
2006.00892v1
2020-06-01
BBN constraints on dark radiation isocurvature
The existence of dark radiation that is completely decoupled from the standard model in the early Universe leaves open the possibility of an associated dark radiation isocurvature mode. We show that the presence of dark radiation isocurvature leads to spatial variation in the primordial abundances of helium and deuteri...
2006.01165v2
2020-06-12
Enhanced Stability of Antiferromagnetic Skyrmion during Its Motion by Anisotropic Dzyaloshinskii Moriya Interaction
Searching for new methods to enhance the stability of antiferromagnetic (AFM) skyrmion during its motion is an important issue for AFM spintronic devices. Herein, the spin polarized current-induced dynamics of a distorted AFM skyrmion is numerically studied, based on the Landau Lifshitz Gilbert simulations of the model...
2006.06938v1
2020-07-02
Spectral Methods for Ranking with Scarce Data
Given a number of pairwise preferences of items, a common task is to rank all the items. Examples include pairwise movie ratings, New Yorker cartoon caption contests, and many other consumer preferences tasks. What these settings have in common is two-fold: a scarcity of data (it may be costly to get comparisons for al...
2007.01346v1
2020-07-23
High Precision Real Time Collision Detection
Collision detection and collision avoidance are essential components in these systems for safe human-robot interactions. Robotics systems that can work "out-of-the-box" without excessive amount of installation and calibration from the experts is highly ideal. For this, we propose a generic, high precision, collision de...
2007.12045v2