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A new way of magnetization switching employing both the spin-transfer torque and the torque by a magnetic field is proposed. The solution of the Landau-Lifshitz-Gilbert equation shows that the dynamics of the magnetization in the initial…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Hirofumi Morise , Shiho Nakamura

In this paper, we consider stochastic optimal control of systems driven by stochastic differential equations with irregular drift coefficient. We establish a necessary and sufficient stochastic maximum principle. To achieve this, we first…

Optimization and Control · Mathematics 2021-01-18 Olivier Menoukeu-Pamen , Ludovic Tangpi

We present an extension to simple s-d models, aiming at simulating ultrafast magnetization dynamics and spin transport in metallic heterostructures. In particular, we consider an alternative spin dissipation channel due to a finite exchange…

Materials Science · Physics 2023-06-14 Quentin Remy

A stochastic control of the vibrational motion for a single trapped ion/atom is proposed. It is based on the possibility to continously monitor the motion through a light field meter. The output from the measurement process should be then…

Quantum Physics · Physics 2007-05-23 S. Mancini

In this paper we combine two main topics in mechanics and optimal control theory: contact Hamiltonian systems and Pontryagin Maximum Principle. As an important result, among others, we develop a contact Pontryagin Maximum Principle that…

Optimization and Control · Mathematics 2020-06-26 Manuel de León , Manuel Lainz , Miguel C. Muñoz-Lecanda

Spin transfer torque and spin pumping are central reciprocal phenomena in spintronics. These phenomena occur in hybrid systems of normal metals and magnets. Spin transfer is the conversion of spin currents in metals to a torque on the…

Mesoscale and Nanoscale Physics · Physics 2022-08-17 Arne Brataas

In magnetic topological insulators, quantized electronic transport is interwined with spontaneous magnetic ordering, as magnetization controls band gaps, hence band topology, through the exchange interaction. We show that considering the…

Mesoscale and Nanoscale Physics · Physics 2021-01-20 Yu-Hang Li , Ran Cheng

In recent years, the optical control of exchange interactions has emerged as an exciting new direction in the study of the ultrafast optical control of magnetic order. Here we review recent theoretical works on antiferromagnetic systems,…

Strongly Correlated Electrons · Physics 2017-10-10 Johan. H. Mentink

Controlling spin currents, i.e., the flow of spin angular momentum, in small magnetic devices is the principal objective of spin electronics, a main contender for future energy efficient information technologies. Surprisingly, a pure spin…

Electrical control of photogenerated THz spin current pulses from a spintronic emitter has been at the forefront for the development of scalable, cost-efficient, wideband opto-spintronics devices. Artificially combined ferroelectric and…

Optimal control theory deals with finding protocols to steer a system between assigned initial and final states, such that a trajectory-dependent cost function is minimized. The application of optimal control to stochastic systems is an…

Statistical Mechanics · Physics 2024-09-18 Julia Sanders , Marco Baldovin , Paolo Muratore-Ginanneschi

Recent measurements in current-driven spin valves demonstrate magnetization fluctuations that deviate from semiclassical predictions. We posit that the origin of this deviation is spin shot noise. On this basis, our theory predicts that…

Mesoscale and Nanoscale Physics · Physics 2019-02-25 Alireza Qaiumzadeh , Arne Brataas

The spin torque switching rate of an in-plane magnetized system in the presence of an applied field is derived by solving the Fokker-Planck equation. It is found that three scaling currents are necessary to describe the current dependence…

Mesoscale and Nanoscale Physics · Physics 2014-01-13 Tomohiro Taniguchi , Hiroshi Imamura

Magnetic nanomaterials can be used in the construction of devices for information processing and memory storage. For this purpose, they have to enjoy two contradictory properties, from one side being able of keeping for long time…

Mesoscale and Nanoscale Physics · Physics 2023-09-28 V. I. Yukalov , E. P. Yukalova

Collective excitations in magnetic materials can be investigated by means of inelastic neutron scattering. We show that this experimental method gives access to the complete spectrum of magnetic fluctuations through the energy- and…

Strongly Correlated Electrons · Physics 2007-05-23 B. Roessli , P. Böni

We consider the Vlasov-Poisson system that is equipped with an external magnetic field to describe the time evolution of the distribution function of a plasma. An optimal control problem where the external magnetic field is the control…

Optimization and Control · Mathematics 2021-10-12 Patrik Knopf , Jörg Weber

The problem of metastability for a stochastic dynamics with a parallel updating rule is addressed in the Freidlin--Wentzel regime, namely, finite volume, small magnetic field, and small temperature. The model is characterized by the…

Statistical Mechanics · Physics 2015-05-13 Emilio N. M. Cirillo , Cristian Spitoni , Francesca R. Nardi

A stochastic optimal control problem for incompressible Newtonian channel flow past a circular cylinder is used as a prototype optimal control problem for the stochastic Navier-Stokes equations. The inlet flow and the rotation speed of the…

Optimization and Control · Mathematics 2024-03-13 Liuhong Chen , Ju Ming , Max D. Gunzburger

In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order…

Mathematical Physics · Physics 2015-05-14 L. Colombo , D. Martin de Diego , M. Zuccalli

In this article, we review recent theoretical research on photocontrol of magnetism in several spin-charge coupled systems. The control of magnetism with light has been a central issue in condensed-matter physics, attracting enormous…

Strongly Correlated Electrons · Physics 2025-05-09 Masahito Mochizuki
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