IA Scholar Query: The Complexity of Ferromagnetic Two-spin Systems with External Fields.
https://scholar.archive.org/
Internet Archive Scholar query results feedeninfo@archive.orgThu, 24 Nov 2022 00:00:00 GMTfatcat-scholarhttps://scholar.archive.org/help1440Iron-Based Ceramic Composite Nanomaterials for Magnetic Fluid Hyperthermia and Drug Delivery
https://scholar.archive.org/work/ofmh7f4rt5hz5pc5ceeqkmuokq
Because of the unique physicochemical properties of magnetic iron-based nanoparticles, such as superparamagnetism, high saturation magnetization, and high effective surface area, they have been applied in biomedical fields such as diagnostic imaging, disease treatment, and biochemical separation. Iron-based nanoparticles have been used in magnetic resonance imaging (MRI) to produce clearer and more detailed images, and they have therapeutic applications in magnetic fluid hyperthermia (MFH). In recent years, researchers have used clay minerals, such as ceramic materials with iron-based nanoparticles, to construct nanocomposite materials with enhanced saturation, magnetization, and thermal effects. Owing to their unique structure and large specific surface area, iron-based nanoparticles can be homogenized by adding different proportions of ceramic minerals before and after modification to enhance saturation magnetization. In this review, we assess the potential to improve the magnetic properties of iron-based nanoparticles and in the preparation of multifunctional composite materials through their combination with ceramic materials. We demonstrate the potential of ferromagnetic enhancement and multifunctional composite materials for MRI diagnosis, drug delivery, MFH therapy, and cellular imaging applications.Ming-Hsien Chan, Chien-Hsiu Li, Yu-Chan Chang, Michael Hsiaowork_ofmh7f4rt5hz5pc5ceeqkmuokqThu, 24 Nov 2022 00:00:00 GMTAn entropic approach to analyze phase transitions in the q = 3 Potts model
https://scholar.archive.org/work/qlen4hyuvzhafooepmffbjmqk4
Boltzmann's microcanonical entropy is the link between statistical physics and thermodynamics, forasmuch as the behavior of any thermodynamic quantity is directly related to the number of microscopic configurations. Accordingly, in this work, we investigate the behavior of the logarithm of the density of states of the three-state Potts model with an external field applied to one of the states using joint entropic simulations based on the Wang-Landau algorithm. Our analysis reveals that the microcanonical entropy curve is detachable, and each resulting path is related to the formation of clusters. Such a description is consistent with the energy-entropy argument related to the inception of a phase transition. When the external field is reversed and strong, the observed phase transition is from an ordered configuration to cluster formations. The behavior of the microcanonical inverse temperature indicates both first and second-order phase transitions occurring at different temperatures for high values of the external field.L. S. Ferreira, L. N. Jorge, C. J. DaSilva, A. A. Caparicawork_qlen4hyuvzhafooepmffbjmqk4Wed, 23 Nov 2022 00:00:00 GMTMachine learning phase transitions of the three-dimensional Ising universality class
https://scholar.archive.org/work/ai3fznhqenbfrn6l23y3qox3by
Exploration of the QCD phase diagram and the critical point is one of the main goals in current relativistic heavy-ion collisions. The QCD critical point is expected to belong to a three-dimensional (3D) Ising universality class. Machine learning techniques are found to be powerful in distinguishing different phases of matter and provide a new way on the study of phase diagram. We investigate phase transitions in the 3D cubic Ising model by using supervised learning methods. It is found that a 3D convolutional neural network can be trained to well predict physical quantities in different spin configurations. With a uniform neural network architecture, it can encode phases of matter and identify both the second- and the first-order phase transitions. The important features that discriminate different phases in the classification processes are investigated. These findings could help to study and understand the QCD phase transitions in relativistic heavy-ion collisions.Xiaobing Li, Ranran Guo, Yu Zhou, Kangning Liu, Jia Zhao, Fen Long, Yuanfang Wu, Zhiming Liwork_ai3fznhqenbfrn6l23y3qox3byWed, 23 Nov 2022 00:00:00 GMTAnatomy of spin wave driven magnetic texture motion via magnonic torques
https://scholar.archive.org/work/t42daanwzrgm5hz2a2eguyrtcm
The interplay between spin wave and magnetic texture represents the information exchange between the fast and slow dynamical parts of magnetic systems. Here we formulate a set of magnonic torques acting on background magnetic texture, by extracting time-invariant information from the fast precessing spin waves. Under the frame of magnonic torques, we use theoretical formulations and micromagnetic simulations to investigate the spin wave driven domain wall motion in two typical symmetry-breaking situations: the rotational symmetry broken by the Dzyaloshinkii-Moriya interaction, and the translational symmetry broken by magnetic damping. The torque-based microscopic analyses provide compact yet quantitative tools to reinterpret the magnetic texture dynamics induced by spin wave, beyond the conventional framework of global momentum conservation.Jin Lan, Hanxu Aiwork_t42daanwzrgm5hz2a2eguyrtcmWed, 23 Nov 2022 00:00:00 GMTMicroscopic field theory for structure formation in systems of self-propelled particles with generic torques
https://scholar.archive.org/work/7dhgno7m4zad7d6hv4bpspwmsy
We derive a dynamical field theory for self-propelled particles subjected to generic torques and forces by explicitly coarse-graining their microscopic dynamics, described by a many-body Fokker-Planck equation. The model includes both intrinsic torques inducing self-rotation, as well as interparticle torques leading to, for instance, the local alignment of particles' orientations. Within this approach, although the functional form of the pairwise interactions does not need to be specified, one can directly map the parameters of the field theory onto the parameters of particle-based models. We perform a linear stability analysis of the homogeneous solution of the field equations and find both long-wavelength and short-wavelength instabilities. The former signals the emergence of a macroscopic structure, which we associate with motility-induced phase separation, while the second one signals the growth of a finite structure with a characteristic size. Intrinsic torques hinder phase separation, pushing the onset of the long-wavelength instability to higher activities. Further, they generate finite-sized structures with a characteristic size proportional to both the self-propulsion velocity and the inverse of the self-rotation frequency. Our results show that a general mechanism might explain why chirality tends to suppress motility-induced phase separation but instead promotes the formation of non-equilibrium patterns.Elena Sesé Sansa, Demian Levis, Ignacio Pagonabarragawork_7dhgno7m4zad7d6hv4bpspwmsyTue, 22 Nov 2022 00:00:00 GMTFractional Topology in interacting 1D Superconductors
https://scholar.archive.org/work/kju5sqqypfcjbmlmfbgyijeguu
We investigate the topological phases of two one-dimensional (1D) interacting superconducting wires, and propose topological invariants directly measurable from ground state correlation functions. These numbers remain powerful tools in the presence of couplings and interactions. We show with the density matrix renormalization group that the double critical Ising (DCI) phase discovered in [1] is a fractional topological phase with gapless Majorana modes in the bulk and a one-half topological invariant per wire. Using both numerics and quantum field theoretical methods we show that the phase diagram remains stable in the presence of an inter-wire hopping amplitude t_ at length scales below ∼ 1/t_. A large inter-wire hopping amplitude results in the emergence of two integer topological phases hosting one edge mode per boundary, shared between both wires. At large interactions the two wires are described by Mott physics, with the t_ hopping amplitude resulting in a paramagnetic order.Frederick del Pozo, Loïc Herviou, Karyn Le Hurwork_kju5sqqypfcjbmlmfbgyijeguuTue, 22 Nov 2022 00:00:00 GMTNon-equilibrium boundary driven quantum systems: models, methods and properties
https://scholar.archive.org/work/wydzomtne5hihiet3j5e2jonsq
Recent years have seen tremendous progress in the theoretical understanding of quantum systems driven dissipatively by coupling them to different baths at their edges. This was possible because of the concurrent advances in the models used to represent these systems, the methods employed, and the analysis of the emerging phenomenology. Here we aim to give a comprehensive review of these three integrated research directions. We first provide an overarching view of the models of boundary-driven open quantum systems, both in the weak and strong coupling regimes. This is followed by a review of state-of-the-art analytical and numerical methods, both exact, perturbative and approximate. Finally, we discuss the transport properties of some paradigmatic one-dimensional chains, with an emphasis on disordered and quasiperiodic systems, the emergence of rectification and negative differential conductance, and the role of phase transitions, and we give an outlook on further research options.Gabriel T. Landi, Dario Poletti, Gernot Schallerwork_wydzomtne5hihiet3j5e2jonsqTue, 22 Nov 2022 00:00:00 GMTThe Duel of Magnetic Interactions Structural Instabilities: Itinerant Frustration in the Triangular Lattice Compound LiCrSe_2
https://scholar.archive.org/work/dkzryexiz5bdpnfux4uvokz7lu
The recent synthesis of the chromium selenide compound LiCrSe_2 constitutes a valuable addition to the ensemble of two-dimensional triangular lattice antiferromagnets (2D-TLA). In this work we present the very first comprehensive study of the combined low temperature nuclear and magnetic structure established in this material. Details on the connection between Li-ion dynamics and structural changes are also presented along with a direct link between atomic structure and spin order via a strong magnetoelastic coupling. LiCrSe_2 was found to undergo a first order structural transition from a trigonal crystal system with space group P3̅m1 to a monoclinic one with space group C2/m at T_ s=30 K. Such restructuring of the lattice is accompanied by a magnetic transition at T_ N=30 K, with the formation of a complex spin arrangement for the Cr^3+ moments. Refinement of the magnetic structure with neutron diffraction data and complementary muon spin rotation analysis reveal the presence of two incommensurate magnetic domains with a up-up-down-down arrangement of the spins with ferromagnetic (FM) double chains coupled antiferromagnetically (AFM). In addition to this unusual arrangement, the spin axial vector is modulated both in direction and modulus, resulting in a spin density wave-like order with periodic suppression of the Cr moment along the chains. This behavior is believed to appear as a result of strong competition between direct exchange AFM and superexchange FM couplings established between both nearest neighbor and next nearest neighbor Cr^3+ ions. We finally conjecture that the resulting magnetic order is stabilized via subtle vacancy/charge order within the Li layers, potentially causing a mix of two different magnetic phases within the sample.E. Nocerino, S. Kobayashi, C. Witteveen, O. K. Forslund, N. Matsubara, C. Tang, T. Matsukawa, A. Hoshikawa, A. Koda, K. Yoshimura, I. Umegaki, Y. Sassa, F. O. von Rohr, V. Pomjakushin, J. H. Brewer, J. Sugiyama, M. Månssonwork_dkzryexiz5bdpnfux4uvokz7luMon, 21 Nov 2022 00:00:00 GMTMagnetoelectric Cavity Magnonics in Skyrmion Crystals
https://scholar.archive.org/work/porp3oux65gtjm3cjvfyzdtjey
We present a theory of magnetoelectric magnon-photon coupling in cavities hosting noncentrosymmetric magnets. Analogously to nonreciprocal phenomena in multiferroics, the magnetoelectric coupling is time-reversal and inversion asymmetric. This asymmetry establishes a means for exceptional tunability of magnon-photon coupling, which can be switched on and off by reversing the magnetization direction. Taking the multiferroic skyrmion host Cu 2 OSeO 3 with ultralow magnetic damping as an example, we reveal the electrical activity of skyrmion eigenmodes and propose it for magnon-photon splitting of "magnetically dark" elliptic modes. Furthermore, we predict a cavity-induced magnon-magnon coupling between magnetoelectrically active skyrmion excitations. We discuss applications in quantum information processing by proposing protocols for all-electrical magnon-mediated photon quantum gates, and a photon-mediated SPLIT operation of magnons. Our study highlights magnetoelectric cavity magnonics as a novel platform for realizing quantum-hybrid systems and the coherent transduction between photons and magnons in topological magnetic textures.Tomoki Hirosawa, Alexander Mook, Jelena Klinovaja, Daniel Losswork_porp3oux65gtjm3cjvfyzdtjeyMon, 21 Nov 2022 00:00:00 GMTFerromagnetic frozen structures from the dipolar hard spheres fluid at moderate and small volume fractions
https://scholar.archive.org/work/jp5qmuy26fgcrcxrz6s4vhukk4
We study the magnetic phase diagram of an ensemble of dipolar hard spheres (DHS) with or without uniaxial anisotropy and frozen in position on a disordered structure by tempered Monte Carlo simulations. The crucial point is to consider an anisotropic structure, obtained from the liquid state of the dipolar hard spheres fluid, frozen in its polarized state at low temperature. The freezing inverse temperature β_f determines the degree of anisotropy of the structure which is quantified through a structural nematic order parameter, λ_s. The case of the non zero uniaxial anisotropy is considered only in its infinitely strong strength limit where the system transforms in a dipolar Ising model (DIM). The important finding of this work is that both the DHS and the DIM with a frozen structure build in this way present a ferromagnetic phase at volume fractions below the threshold value where the corresponding isotropic DHS systems exhibit a spin glass phase at low temperature.Jean-Guillaume Malherbe, Vincent Russier, Juan-Jose Alonsowork_jp5qmuy26fgcrcxrz6s4vhukk4Mon, 21 Nov 2022 00:00:00 GMTSublattice-enriched tunability of bound states in second-order topological insulators and superconductors
https://scholar.archive.org/work/6oan43oabjcjxhuyn5d7cy2dc4
Bound states at sharp corners have been widely viewed as the hallmark of two-dimensional second-order topological insulators and superconductors. In this work, we show that the existence of sublattice degrees of freedom can enrich the tunability of bound states on the boundary and hence lift the constraint on their locations. We take the Kane-Mele model with honeycomb-lattice structure to illustrate the underlying physics. With the introduction of an in-plane exchange field to the model, we find that the boundary Dirac mass induced by the exchange field has a sensitive dependence on the boundary sublattice termination. We find that the sensitive sublattice dependence can lead bound states to emerge at a specific type of boundary defects named as sublattice domain walls if the exchange field is of ferromagnetic nature, even in the absence of any sharp corner on the boundary. Remarkably, this sensitive dependence of the boundary Dirac mass on the boundary sublattice termination allows the positions of bound states to be manipulated to any place on the boundary for an appropriately-designed sample. With a further introduction of conventional s-wave superconductivity to the model, we find that, no matter whether the exchange field is ferromagnetic, antiferromagnetic, or ferrimagnetic, highly controllable Majorana zero modes can be achieved at the sublattice domain walls. Our work reshapes the understanding of boundary physics in second-order topological phases, and meanwhile opens potential avenues to realize highly controllable bound states for potential applications.Di Zhu, Majid Kheirkhah, Zhongbo Yanwork_6oan43oabjcjxhuyn5d7cy2dc4Sun, 20 Nov 2022 00:00:00 GMTSpin-wave spectra in antidot lattice with inhomogeneous perpendicular magnetocrystalline anisotropy
https://scholar.archive.org/work/s2w7ln4fdnaxjpku5hgyay2psu
Magnonic crystals are structures with periodically varied magnetic properties that are used to control collective spin-wave excitations. With micromagnetic simulations, we study spin-wave spectra in a 2D antidot lattice based on a multilayered thin film with perpendicular magnetic anisotropy (PMA). We show that the modification of the PMA near the antidot edges introduces interesting modifications to the spin-wave spectra, even in a fully saturated state. In particular, the spectra split in two types of excitations, bulk modes with amplitude concentrated in a homogeneous part of antidot lattice, and edge modes with an amplitude localized in the rims of reduced PMA at the antidot edges. Their dependence on the geometrical or material parameters is distinct but at resonance conditions fulfilled, we found strong hybridization between bulk and radial edge modes. Interestingly, the hybridization between the fundamental modes in bulk and rim is of magnetostatic origin but the exchange interactions determine the coupling between higher-order radial rim modes and the fundamental bulk mode of the antidot lattice.M. Moalic, M.Krawczyk, M. Zelentwork_s2w7ln4fdnaxjpku5hgyay2psuSun, 20 Nov 2022 00:00:00 GMTInfuence of pressure on magnetic phase transitions in the ferromagnetic superconductor UGe_2 – phenomenological approach
https://scholar.archive.org/work/jvcurtppk5fnfo65ritxnomoka
We propose a thermodynamic model of free energy expansion up to eighth order of magnetisation to describe the complex magnetic phase transitions in ferromagnetic superconductor UGe_2. The model successfully describes transitions between ordered phases which take place without changing of magnetic structure but only of magnetisation which is the case of UGe_2 where two magnetic phases with same structure but with different magnitude occur with decreasing of temperature. We consider the infuence of pressure on magnetic transitions in the simplest form of including it only in pressure dependence of Curie temperature for the transition between the paramagnetic and themagnetic phase with the lower magnetic moment FM1. Our results show that for pressures lower than some limiting pressure the transition betweenlow-and high-magnetisation phase remains of crossover type. Above this limiting pressure this transition changes to real thermodynamic transition of first order.Diana V. Shopovawork_jvcurtppk5fnfo65ritxnomokaSat, 19 Nov 2022 00:00:00 GMTJosephson diode effect on the surface of topological insulators
https://scholar.archive.org/work/kjkbla55tffxtfapaxhmjejhei
We study the Josephson diode effect in a superconductor-normal metal-superconductor junction on the surface of a three-dimensional topological insulator when an in-plane magnetic field is applied. We find strong dependence of the current-phase relation on the transverse momentum and sign changes of the quality factor as the magnitude of magnetic field varies. These sign changes require a long junction length and are absent in the one-dimensional limit. Our work indicates that high-dimensional rectification systems have rich properties due to multiple transport channels, which can be used for designing realistic superconducting diode devices.Bo Lu, Satoshi Ikegaya, Pablo Burset, Yukio Tanaka, Naoto Nagaosawork_kjkbla55tffxtfapaxhmjejheiSat, 19 Nov 2022 00:00:00 GMTPressure-Induced Mott Insulator-to-Metal Transition in van der Waals compound CoPS_3
https://scholar.archive.org/work/4c54h7zoqvet5ibjxn4sa2ymam
We have studied the Mott insulator-to-metal transition (IMT) and concomitant evolution of structural properties under high pressure in the van der Waals compound CoPS_3 through in-situ electrical resistance, Hall effect, magnetoresistance, X-ray diffraction, and Raman scattering measurements. CoPS_3, a native antiferromagnet at 122 K under ambient conditions, exhibits an IMT at 7 GPa, coinciding with a C2/m → P3 structural transformation and a 2.4% reduction in the volume per formula unit, indicative of a Mott transition. This metallic CoPS_3 observed under high pressure is a hole-dominant conductor with multiple conduction bands. The linear magnetoresistance (LMR), as well as the small volume collapse at the IMT, suggests the incomplete high-spin → low-spin transition in the metallic phase. Thus, the metallic CoPS_3 may possess an inhomogeneous magnetic moment distribution and short-range magnetic ordering (SRO). By revealing the high-pressure phase and electrical transport property of CoPS_3, this report summarizes the comprehensive phase diagram of MPS_3 (M = V, Mn, Fe, Co, Ni, and Cd) that metalize via Mott transition.Takahiro Matsuoka, Rahul Rao, Michael A. Susner, Benjamin S. Conner, Dongzhou Zhang, David Mandruswork_4c54h7zoqvet5ibjxn4sa2ymamSat, 19 Nov 2022 00:00:00 GMTThe Microwave Absorption in Composites with Finemet Alloy Particles and Carbon Nanotubes
https://scholar.archive.org/work/fi4edwgzsfa6rfa5zyuj426kzu
The absorption of waves of the centimeter and millimeter wavebands in composites with Finemet alloy particles and carbon nanotubes has been studied. It has been established that ferromagnetic resonance and antiresonance are observed in such composites. A method is proposed for calculating the effective dynamic magnetic permeability of a composite containing both a random distribution of ferromagnetic particles and a part of the particles oriented in the same way. In the approximation of effective parameters, the dependences of the transmission and reflection coefficients of microwaves are calculated. It is shown that the theoretical calculation confirms the existence of resonant features of these dependences caused by ferromagnetic resonance and antiresonance. The theory based on the introduction of effective parameters satisfactorily describes the course of the field dependence of the coefficients and the presence of resonance features in these dependences. The frequency dependence of the complex permittivity of the composite is determined. The dependence of the complex magnetic permeability on the magnetic field for millimeter-wave frequencies is calculated.Anatoly B. Rinkevich, Dmitry V. Perov, Evgeny A. Kuznetsov, Yulia V. Korkh, Anna S. Klepikova, Yury I. Ryabkovwork_fi4edwgzsfa6rfa5zyuj426kzuFri, 18 Nov 2022 00:00:00 GMTIncommensurate and multiple-q magnetic misfit order in the frustrated quantum-spin-ladder material antlerite, Cu_3SO_4(OH)_4
https://scholar.archive.org/work/4tovul3nobaezny2g3kzeku3ay
In frustrated magnetic systems, the competition amongst interactions can introduce extremely high degeneracy and prevent the system from readily selecting a unique ground state. In such cases, the magnetic order is often exquisitely sensitive to the balance among the interactions, allowing tuning among novel magnetically ordered phases. In antlerite, Cu_3SO_4(OH)_4, Cu^2+ (S=1/2) quantum spins populate three-leg zigzag ladders in a highly frustrated quasi-one-dimensional structural motif. We demonstrate that at zero applied field, in addition to its recently reported low-temperature phase of coupled ferromagnetic and antiferromagnetic spin chains, this mineral hosts an incommensurate helical+cycloidal state, an idle-spin state, and a multiple-q phase which is the magnetic analog of misfit crystal structures. The antiferromagnetic order on the central leg is reentrant. The high tunability of the magnetism in antlerite makes it a particularly promising platform for pursuing exotic magnetic order.Anton A. Kulbakov, Elaheh Sadrollahi, Florian Rasch, Maxim Avdeev, Sebastian Gaß, Laura Teresa Corredor Bohorquez, Anja U. B. Wolter, Manuel Feig, Roman Gumeniuk, Hagen Poddig, Markus Stötzer, F. Jochen Litterst, Inés Puente-Orench, Andrew Wildes, Eugen Weschke, Jochen Geck, Dmytro S. Inosov, Darren C. Peetswork_4tovul3nobaezny2g3kzeku3ayFri, 18 Nov 2022 00:00:00 GMTDiverse Behaviors in Non-Uniform Chiral and Non-Chiral Swarmalators
https://scholar.archive.org/work/da67nrorizavzehl766gxdzf5u
We study the emergent behaviors of a population of swarming coupled oscillators, dubbed 'swarmalators'. Previous work considered the simplest, idealized case: identical swarmalators with global coupling. Here we expand this work by adding more realistic features: local coupling, non-identical natural frequencies, and chirality. This more realistic model generates a variety of new behaviors including lattices of vortices, beating clusters, and interacting phase waves. Similar behaviors are found across natural and artificial micro-scale collective systems, including social slime mold, spermatozoa vortex arrays, and Quincke rollers. Our results indicate a wide range of future use cases, both to aid characterization and understanding of natural swarms, and to design complex interactions in collective systems from soft and active matter to micro-robotics.Steven Ceron, Kevin O'Keeffe, Kirstin Petersenwork_da67nrorizavzehl766gxdzf5uThu, 17 Nov 2022 00:00:00 GMTStrain Fields and Critical Phenomena in Manganites I: Spin-Lattice Hamiltonians
https://scholar.archive.org/work/pbbd4j4no5fwdpb76sjqeaqyna
We use a model Hamiltonian to study critical phenomena in manganites. This Hamiltonian includes long-range strain interactions, and a coupling between the magnetic order parameter and the strain field. We perform a perturbative renormalization group (RG) analysis and calculate the static critical exponents, correct to the one-loop level. We compare our RG results with many experiments on doped manganite critical systems. Our theory is in excellent agreement with the experimental values for the critical exponents.Rohit Singh, Sanjay Puriwork_pbbd4j4no5fwdpb76sjqeaqynaThu, 17 Nov 2022 00:00:00 GMTQuantum Metrology Protected by Hilbert Space Fragmentation
https://scholar.archive.org/work/ecnomty3erfrdnfi2om5ndrg3a
We propose an entanglement-enhanced sensing scheme that is robust against spatially inhomogeneous always-on Ising interactions. Our strategy is to tailor coherent quantum dynamics employing the Hilbert-space fragmentation (HSF), a recently recognized mechanism that evades thermalization in kinetically constrained many-body systems. Specifically, we analytically show that the emergent HSF caused by strong Ising interactions enables us to design a stable state where part of the spins is effectively decoupled from the rest of the system. Using the decoupled spins as a probe to measure a transverse field, we demonstrate that the Heisenberg limited sensitivity is achieved without suffering from thermalization.Atsuki Yoshinaga, Yuichiro Matsuzaki, Ryusuke Hamazakiwork_ecnomty3erfrdnfi2om5ndrg3aThu, 17 Nov 2022 00:00:00 GMT