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Optimal control of magnetizing current for minimizing induction motor power losses during load torque step change was developed. Obtained strategy has feedback form and is exactly optimal of ideal speed controller performance and absence of…

Systems and Control · Computer Science 2014-04-21 Alex Borisevich , Gernot Schullerus

Decoherence is a major challenge for quantum technologies. A way to mitigate its negative impact is by employing quantum optimal control. The decoherence dynamics varies significantly based on the characteristics of the surrounding…

We study the agility of current-tunable oscillators based on a magnetic vortex orbiting around a point contact in spin-valves. Theory predicts frequency-tuning by currents occurs at constant orbital radius, so an exceptional agility is…

Mesoscale and Nanoscale Physics · Physics 2019-09-11 M. Manfrini , T. Devolder , Joo-Von Kim , P. Crozat , N. Zerounian , C. Chappert , W. Van Roy , L. Lagae , G. Hrkac , T. Schrefl

Electric control of magnetic vortex dynamics in a reproducible way and on an ultrafast time scale is key element in the quest for efficient spintronic devices with low-energy consumption. To be useful the control scheme should ideally be…

Mesoscale and Nanoscale Physics · Physics 2019-07-29 Dongxing Yu , Jiyong Kang , Jamal Berakdar , Chenglong Jia

Measurements of magnetic hysteresis loops in single Co nanoparticles at dilution refrigerator temperatures are presented. The nanoparticles are in electric contact with bulk Al leads via tunnel junctions. The tunnel current versus magnetic…

Mesoscale and Nanoscale Physics · Physics 2012-07-10 F. Tijiwa Birk , W. Jiang , D. Davidović

A spin-polarized current with the polarization perpendicular to the plane of a vortex-state disk results in renormalization of the effective damping for a given magnetization mode, and the effective damping becomes zero if the current…

Materials Science · Physics 2009-11-13 B. A. Ivanov , C. E. Zaspel

This article is aimed at extending the framework of optimal control techniques to the situation where the control field values are restricted to a finite set. We propose a generalization of the standard GRAPE algorithm suited to this…

Optimization and Control · Mathematics 2015-10-28 G. Dridi , M. Lapert , Julien Salomon , D Sugny , S. J. Glaser

We theoretically study the spin-polarized transport through a single-molecule magnet, which is weakly coupled to ferromagnetic leads, by means of the rate-equation approach. We consider both the ferromagnetic and antiferromagnetic…

Mesoscale and Nanoscale Physics · Physics 2012-03-22 Haiqing Xie , Qiang Wang , Bo Chang , Hujun Jiao , J. -Q. Liang

Spin orbit torque (SOT) provides an efficient way of generating spin current that promises to significantly reduce the current required for switching nanomagnets. However, an in-plane current generated SOT cannot deterministically switch a…

Spin-polarized electron transport driven by inhomogeneous magnetic dynamics is discussed in the limit of a large exchange coupling. Electron spins rigidly following the time-dependent magnetic profile experience spin-dependent fictitious…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Yaroslav Tserkovnyak , Matthew Mecklenburg

We apply a recently developed quantum theory of spin transfer torque to study the effect of the quantum noise in spin transfer process on the magnetization switching in spin-torque-driven devices. The quantum noise induces considerable…

Mesoscale and Nanoscale Physics · Physics 2013-07-10 Yong Wang , Yan Zhou , Fu-Chun Zhang

We investigate cooling of a vibrational mode of a magnetic quantum dot by a spin-polarized tunneling charge current, exploiting the interaction between the magnetization and the vibration. The spin-polarized charge current polarizes the…

Mesoscale and Nanoscale Physics · Physics 2014-09-03 J. Brüggemann , S. Weiss , P. Nalbach , M. Thorwart

We theoretically propose a method of rectifying spin current with a linearly-polarized electromagnetic wave in inversion-asymmetric magnetic insulators. To demonstrate the proposal, we consider quantum spin chains as a simple example; these…

Strongly Correlated Electrons · Physics 2019-05-22 Hiroaki Ishizuka , Masahiro Sato

Laser induced ultrafast demagnetization is the process whereby the magnetic moment of a ferromagnetic material is seen to drop significantly on a timescale of $10-100$s of femtoseconds due to the application of a strong laser pulse. If this…

Materials Science · Physics 2016-01-20 P. Elliott , K. Krieger , J. K. Dewhurst , S. Sharma , E. K. U. Gross

The reversal of the magnetization under the influence of a field pulse has been previously predicted to be an incoherent process with several competing phenomena such as domain wall relaxation, spin wave-mediated instability regions, and…

Multiple neuromorphic applications require the tuning of two or more devices to a common signal. Various types of neuromorphic computation can be realized using spintronic oscillators, where the DC current induces magnetization precession,…

We present experimental results and macrospin simulations of the switching characteristics of orthogonal spin-transfer devices incorporating an out-of-plane magnetized polarizing layer and an in-plane magnetized spin valve device at…

Mesoscale and Nanoscale Physics · Physics 2017-11-30 Graham E. Rowlands , Colm A. Ryan , Li Ye , Laura Rehm , Daniele Pinna , Andrew D. Kent , Thomas A. Ohki

We use quantum optimal control theory algorithms to design external electric fields that drive the coupled spin and orbital dynamics of an electron in a double quantum dot, subject to the spin-orbit interaction and Zeeman magnetic fields.…

Mesoscale and Nanoscale Physics · Physics 2016-02-17 J. A. Budagosky , D. V. Khomitsky , E. Ya. Sherman , Alberto Castro

It is shown theoretically that a single a few picoseconds long acoustic pulse can reverse magnetization in a magneto-strictive material Terfenol-D. Following giant magneto-elastic changes of free energy density the magnetization vector is…

Materials Science · Physics 2013-06-28 O. Kovalenko , T. Pezeril , V. V. Temnov

The transition probability of a spin driven by a rotating magnetic field is reformulated. This work shows that, once projection onto the measurement basis is properly accounted for, the laboratory measured probability is governed by both…

Quantum Physics · Physics 2026-04-28 Sunghyun Kim