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We study the dynamics of a spin torque nano oscillator that consists of parallelly magnetized free and pinned layers by numerically solving the associated Landau-Lifshitz-Gilbert-Slonczewski equation in the presence of a field-like torque.…

Mesoscale and Nanoscale Physics · Physics 2022-02-02 R. Arun , R. Gopal , V. K. Chandrasekar , M. Lakshmanan

We use pulsed inductive microwave magnetometry to study the precessional magnetization dynamics of the free layer in CoFeB/MgO/CoFeB based magnetic tunnelling junction stacks with varying MgO barrier thickness. From the field dependence of…

We investigated the effect of using a synthetic ferrimagnetic (SyF) free layer in MgO-based magnetic tunnel junctions (MTJs) on current-induced magnetization switching (CIMS), particularly for application to spin-transfer torque random…

We present an experimental study of phase-locking in a stochastic magnetic oscillator. The system comprises a magnetic tunnel junction with a superparamagnetic free layer, whose magnetization dynamics is driven with spin torques through an…

We show that direct current in a tantalum microstrip can induce steady-state magnetic oscillations in an adjacent nanomagnet through spin torque from the spin Hall effect (SHE). The oscillations are detected electrically via a magnetic…

Materials Science · Physics 2015-06-11 Luqiao Liu , Chi-Feng Pai , D. C. Ralph , R. A. Buhrman

Spin polarized current can excite the magnetization of a ferromagnet through the transfer of spin angular momentum to the local spin system. This pure spin-related transport phenomena leads to alluring possibilities for the achievement of a…

We performed a first-principles study of the tunneling anisotropic magneto-resistance (TAMR) in Ag(Ir,Pt)$/$MgO$/$Fe junctions. Enhanced TAMR with ideal and skewed fourfold angular dependence is found in-plane and out-of-plane TAMR of the…

Applied Physics · Physics 2022-09-21 Hui-Min Tang , Shi-zhuo Wang , Xin-tao Jia

We created epitaxial magnetic tunnel junctions of FeCo/MgO/EuS on MgO buffered Si (100). Tunnel magnetoresistance reached up to 64% at 4.2 K. An unexpected fast drop of magnetoresistance was recorded for MgO thickness above 1 nm, which is…

Materials Science · Physics 2016-08-09 Zhiwei Gao , Yihang Yang , Fen Liu , Qian Xue , Guo-Xing Miao

We study the theoretical conditions to excite a stable self-oscillation in a spin torque oscillator with an in-plane magnetized free layer and a perpendicularly magnetized pinned layer in the presence of magnetic field pointing in an…

Mesoscale and Nanoscale Physics · Physics 2016-05-06 Tomohiro Taniguchi , Hitoshi Kubota

The nonlinear frequency shift coefficient, which represents the strength of the transformation of amplitude fluctuations into phase fluctuations of an oscillator, is measured for MgO-based spin-torque oscillators by analyzing the current…

Materials Science · Physics 2015-05-13 Kiwamu Kudo , Tazumi Nagasawa , Rie Sato , Koichi Mizushima

We demonstrate a simple network-analyzer technique to make quantitative measurements of the bias dependence of spin torque in a magnetic tunnel junction. We apply a microwave current to exert an oscillating spin torque near the…

Mesoscale and Nanoscale Physics · Physics 2012-07-25 Lin Xue , Chen Wang , Yong-Tao Cui , J. A. Katine , R. A. Buhrman , D. C. Ralph

We have fabricated nanoscale magnetic tunnel junctions (MTJs) with an additional fixed magnetic layer added above the magnetic free layer of a standard MTJ structure. This acts as a second source of spin-polarized electrons that, depending…

We study ns scale spin-torque-induced switching in perpendicularly magnetized tunnel junctions (pMTJ). Although the switching voltages match with the macrospin instability threshold, the electrical signatures of the reversal indicate the…

Mesoscale and Nanoscale Physics · Physics 2016-02-03 T. Devolder , Joo-Von Kim , F. Garcia-Sanchez , J. Swerts , W. Kim , S. Couet , G. Kar , A. Furnemont

We report first-principles analysis on the bias dependence of spin-transfer torque (STT) in Fe/MgO/Fe magnetic tunnel junctions. The in-plane STT changes from linear to nonlinear dependence as the bias voltage is increased from zero. The…

Materials Science · Physics 2015-03-19 Xingtao Jia , Ke Xia , Youqi Ke , Hong Guo

We use micromagnetic simulations to map out and compare, the linear and auto-oscillating modes in constriction-based spin Hall nano-oscillators as a function of applied magnetic field with varying magnitude and out-of-plane angle. We…

Mesoscale and Nanoscale Physics · Physics 2018-01-24 Mykola Dvornik , Ahmad A. Awad , Johan Åkerman

We report on a voltage tunable radio-frequency (RF) detector based on a magnetic tunnel junction (MTJ). The spin-torque diode effect is used to excite and/or detect RF oscillations in the magnetic free layer of the MTJ. In order to reduce…

Mesoscale and Nanoscale Physics · Physics 2015-06-22 Witold Skowroński , Marek Frankowski , Jerzy Wrona , Tomasz Stobiecki , Piotr Ogrodnik , Józef Barnaś

There exists a significant challenge in developing efficient magnetic tunnel junctions with low write currents for non-volatile memory devices. With the aim of analysing potential materials for efficient current-operated magnetic junctions…

Mesoscale and Nanoscale Physics · Physics 2017-12-13 Matthew O. A. Ellis , Maria Stamenova , Stefano Sanvito

We show how a charge current through a single antiferromagnetic layer can excite and control self-oscillations. Sustained oscillations with tunable amplitudes and frequencies are possible in a variety of geometries using certain classes of…

Mesoscale and Nanoscale Physics · Physics 2019-03-06 Roberto E. Troncoso , Karsten Rode , Plamen Stamenov , J. Michael D. Coey , Arne Brataas

We report time-resolved measurements of magnetization switching by spin-orbit torques in the absence of an external magnetic field in perpendicularly magnetized magnetic tunnel junctions (MTJ). Field-free switching is enabled by the dipolar…

Mesoscale and Nanoscale Physics · Physics 2020-06-12 Viola Krizakova , Kevin Garello , Eva Grimaldi , Gouri Sankar Kar , Pietro Gambardella

We present a circuit design of a spintronic oscillator based on magnetic tunnel junction. In this design, a dc current is passed through a magnetic tunnel junction which is connected to a feed-back wire below it. Any fluctuation in the…

Mesoscale and Nanoscale Physics · Physics 2018-07-31 D. Dixit , K. Konishi , C. V. Tomy , Y. Suzuki , A. A. Tulapurkar