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We consider a small itinerant ferromagnet exposed to an external magnetic field and strongly driven by a thermally induced spin current. For this model, we derive the quasi-classical equations of motion for the magnetization where the…

Mesoscale and Nanoscale Physics · Physics 2019-01-30 Tim Ludwig , Igor S. Burmistrov , Yuval Gefen , Alexander Shnirman

The linear response of itinerant transition metal ferromagnets to transverse magnetic fields is studied in a self-consistent adiabatic local-density approximation. The susceptibility is calculated from a microscopic Hamiltonian, including…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 Hans Joakim Skadsem , Yaroslav Tserkovnyak , Arne Brataas , Gerrit E. W. Bauer

We present a theoretical framework for equilibrium and nonequilibrium dynamical simulation of quantum states with spin-density-wave (SDW) order. Within a semiclassical adiabatic approximation that retains electron degrees of freedom, we…

Strongly Correlated Electrons · Physics 2018-01-12 Gia-Wei Chern , Kipton Barros , Zhentao Wang , Hidemaro Suwa , Cristian D. Batista

We investigate numerically the magnetisation dynamics of an array of nano-disks interacting through the magneto-dipolar coupling. In the presence of a temperature gradient, the chain reaches a non-equilibrium steady state where energy and…

Statistical Mechanics · Physics 2015-03-03 Simone Borlenghi , Stefano Iubini , Stefano Lepri , Jonathan Chico , Lars Bergqvist , Anna Delin , Jonas Fransson

A composite multiferroic chain with an interfacial linear magneto-electric coupling is used to study the magnetic and electric responses to an external magnetic or electric field. The simulation uses continuous spin dynamics through the…

Mesoscale and Nanoscale Physics · Physics 2015-08-25 Zidong Wang , Malcolm J. Grimson

The classical Landau--Lifshitz equation -- the simplest model of a ferromagnet -- provides an archetypal example for studying transport phenomena. In one-spatial dimension, integrability enables the classification of the spectrum of linear…

Statistical Mechanics · Physics 2024-09-06 Alvise Bastianello , Žiga Krajnik , Enej Ilievski

We study the equilibrium and nonequilibrium electronic transport properties of multiprobe topological systems using a combination of the Landauer-B\"uttiker approach and nonequilibrium Green's functions techniques. We obtain general…

Mesoscale and Nanoscale Physics · Physics 2022-02-25 Leandro R. F. Lima , Caio Lewenkopf

Nonequilibrium statistical mechanics exhibit a variety of complex phenomena far from equilibrium. It inherits challenges of equilibrium, including accurately describing the joint distribution of a large number of configurations, and also…

Statistical Mechanics · Physics 2024-02-08 Ying Tang , Jing Liu , Jiang Zhang , Pan Zhang

Many non-equilibrium processes on scale-free networks present anomalous critical behavior that is not explained by standard mean-field theories. We propose a systematic method to derive stochastic equations for mean-field order parameters…

Disordered Systems and Neural Networks · Physics 2015-05-13 F. Caccioli , L. Dall'Asta

We consider spin dynamics for implementation in an atomistic framework and we address the feasibility of capturing processes in the femtosecond regime by inclusion of moment of inertia. In the spirit of an {\it s-d} -like interaction…

Statistical Mechanics · Physics 2012-02-02 S. Bhattacharjee , L. Nordström , J. Fransson

The significant experimental advances of the last few decades in dealing with the interaction of spin currents and nanomagnets, at the device level, has allowed envisioning a broad class of devices that propose to implement information…

Mesoscale and Nanoscale Physics · Physics 2014-05-28 Srikant Srinivasan , Vinh Diep , Behtash Behin-Aein , Angik Sarkar , Supriyo Datta

Using irreversible thermodynamics we show that current-induced spin transfer torque within a magnetic domain implies spin pumping of current within that domain. This has experimental implications for samples both with conducting leads and…

Other Condensed Matter · Physics 2009-11-13 Wayne M. Saslow

We propose a machine learning based approach to develop the exchange-correlation potential of time dependent density functional theory (TDDFT). The neural network projection from the time-varying electron densities to the corresponding…

Computational Physics · Physics 2020-05-20 Yasumitsu Suzuki , Ryo Nagai , Jun Haruyama

When neural networks are used to model dynamics, properties such as stability of the dynamics are generally not guaranteed. In contrast, there is a recent method for learning the dynamics of autonomous systems that guarantees global…

Machine Learning · Computer Science 2022-03-21 Kenji Kashima , Ryota Yoshiuchi , Yu Kawano

The Landau-Lifshitz equation describes the time-evolution of magnetic dipoles, and can be derived by taking the classical limit of a quantum mechanical spin Hamiltonian. To take this limit, one constrains the many-body quantum state to a…

Strongly Correlated Electrons · Physics 2022-09-21 David Dahlbom , Hao Zhang , Cole Miles , Xiaojian Bai , Cristian D. Batista , Kipton Barros

Deep neural networks are used to model the magnetization dynamics in magnetic thin film elements. The magnetic states of a thin film element can be represented in a low dimensional space. With convolutional autoencoders a compression ratio…

The Landau-Zener transition is a fundamental concept for dynamical quantum systems and has been studied in numerous fields of physics. Here we present a classical mechanical model system exhibiting analogous behaviour using two inversely…

Mesoscale and Nanoscale Physics · Physics 2012-08-10 Thomas Faust , Johannes Rieger , Maximilian J. Seitner , Peter Krenn , Jörg P. Kotthaus , Eva M. Weig

In recent years there has been an increasing interest in nanomachines. Among them, current-driven ones deserve special attention as quantum effects can play a significant role there. Examples of the latter are the so-called adiabatic…

Mesoscale and Nanoscale Physics · Physics 2019-01-09 Lucas J. Fernández-Alcázar , Horacio M. Pastawski , Raúl A. Bustos-Marún

We develop a machine learning algorithm to infer the emergent stochastic equation governing the evolution of an order parameter of a many-body system. We train our neural network to independently learn the directed force acting on the order…

Disordered Systems and Neural Networks · Physics 2024-12-10 Francesco Carnazza , Federico Carollo , Sabine Andergassen , Georg Martius , Miriam Klopotek , Igor Lesanovsky

We study ferromagnetic transition in three-dimensional double-exchange model. The influence of strong spin fluctuations on conduction electrons is described in coherent potential approximation. In the framework of thermodynamic approach we…

Statistical Mechanics · Physics 2013-05-29 Mark Auslender , Eugene Kogan