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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

A theoretical study on how synchronization and resonance-like phenomena in superparamagnetic tunnel junctions can be driven by spin-transfer torques is presented. We examine the magnetization of a superparamagnetic free layer that reverses…

Mesoscale and Nanoscale Physics · Physics 2016-09-21 Artur Accioly , Nicolas Locatelli , Alice Mizrahi , Damien Querlioz , Luis G. Pereira , Julie Grollier , Joo-Von Kim

We address the shot noise in the tunneling current through a localized spin, pertaining to recent experiments on magnetic adatoms and single molecular magnets. We show that both uncorrelated and spin-correlated scattering processes…

Mesoscale and Nanoscale Physics · Physics 2018-03-16 S. Pradhan , J. Fransson

Using non-equilibrium Green functions we calculate the spin-polarized current and shot noise in a ferromagnet--quantum-dot--ferromagnet (FM-QD-FM) system. Both parallel (P) and antiparallel (AP) magnetic configurations are considered.…

Mesoscale and Nanoscale Physics · Physics 2008-10-31 F. M. Souza , A. P. Jauho , J. C. Egues

When an electric current passes across a potential barrier, the partition process of electrons at the barrier gives rise to the shot noise, reflecting the discrete nature of the electric charge. Here we report the observation of excess shot…

We propose a generalized stochastic Landau-Lifshitz equation and its corresponding Fokker-Planck equation for the magnetization dynamics in the presence of spin transfer torques. Since the spin transfer torque can pump a magnetic energy…

Materials Science · Physics 2009-11-10 Z. Li , S. Zhang

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

Thermal-bias-induced spin angular momentum transfer between a paramagnetic metal and ferromagnetic insulator is studied theoretically based on the stochastic Landau-Lifshitz-Gilbert (LLG) phenomenology. Magnons in the ferromagnet establish…

Mesoscale and Nanoscale Physics · Physics 2013-08-14 Silas Hoffman , Koji Sato , Yaroslav Tserkovnyak

We present a complete theory of the spin torque phenomena in a ultrasmall nanomagnet coupled to non-collinear ferromagnetic electrodes through tunnelling junctions. This model system can be described by a simple microscopic model which…

Mesoscale and Nanoscale Physics · Physics 2008-02-22 O. Parcollet , X. Waintal

We calculate the contribution to the spin transfer torque from sequential tunneling through impurities in a magnetic tunnel junction. For a junction with weakly polarized ferromagnetic contacts, the torque is found to be in the plane…

Mesoscale and Nanoscale Physics · Physics 2009-07-31 Turan Birol , Piet W. Brouwer

We consider a small metallic particle (quantum dot) where ferromagnetism arises as a consequence of Stoner instability. When the particle is connected to electrodes, exchange of electrons between the particle and the electrodes leads to a…

Mesoscale and Nanoscale Physics · Physics 2009-03-30 D. M. Basko , M. G. Vavilov

In this paper we show that the spin transfer torque can be described by a pseudo magnetic field, proportional to the magnetic moment of the itinerant electrons that enters the Landau-Lifshitz-Gilbert equation in the same way as other…

Mesoscale and Nanoscale Physics · Physics 2008-11-24 Sayeef Salahuddin , Deepanjan Datta , Supriyo Datta

We develop a theoretical formula of spin Hall torque in the presence of two ferromagnets. While the direction of the conventional spin Hall torque always points to the in-plane direction, the present system enables to manipulate the torque…

Mesoscale and Nanoscale Physics · Physics 2016-06-27 Tomohiro Taniguchi , Seiji Mitani , Masamitsu Hayashi

By scattering theory we show that spin current noise in normal electric conductors in contact with nanoscale ferromagnets increases the magnetization noise by means of a fluctuating spin-transfer torque. Johnson-Nyquist noise in the spin…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Jorn Foros , Arne Brataas , Yaroslav Tserkovnyak , Gerrit E. W. Bauer

Spin-polarized current effect is studied on the static and dynamic magnetization of the antiferromagnet in a ferromagnet - antiferromagnet nanojunction. The macrospin approximation is generalized to antiferromagnets. Canted…

Materials Science · Physics 2011-12-13 E. M. Epshtein , Yu. V. Gulyaev , P. E. Zilberman

A semiclassical theory of the low frequency shot noise in ferromagnet - normal metal systems is formulated. Non-collinear magnetization directions of the ferromagnetic leads, arbitrary junctions and the elastic and inelastic scattering…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Yaroslav Tserkovnyak , Arne Brataas

Non-equilibrium spin-dependent transport in magnetic tunnel junctions comprising a ferroelectric barrier is theoretically investigated. The exact solutions of the free electron Schr\"odinger equation for electron tunneling in the presence…

Mesoscale and Nanoscale Physics · Physics 2012-11-20 A. Useinov , A. Manchon

We calculate the magnetization torque due to the spin polarization of the itinerant electrons by deriving the kinetic spin Bloch equations based on the $s$-$d$ model. We find that the first-order gradient of the magnetization inhomogeneity…

Materials Science · Physics 2011-02-15 K. Shen , G. Tatara , M. W. Wu

We investigate the possibility of exciting self-oscillation in a perpendicular ferromagnet by the spin Hall effect on the basis of a nonlinear analysis of the Landau-Lifshitz-Gilbert (LLG) equation. In the self-oscillation state, the energy…

Mesoscale and Nanoscale Physics · Physics 2015-03-13 Tomohiro Taniguchi

Following the theoretical approach by Xiao et al [Phys. Rev. B 81, 214418 (2010)] to the spin Seebeck effect, we calculate the mean value of the total spin current flowing through a normalmetal/ ferromagnet interface. The spin current…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 L. Chotorlishvili , Z. Toklikishvili , V. K. Dugaev , J. Barnas , S. Trimper , J. Berakdar