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Experiments have shown that the tunneling current in a Co/Al$_2$O$_3$ magnetic tunneling junction (MTJ) is positively spin polarized, opposite to what is intuitively expected from standard tunneling theory which gives the spin polarization…

Mesoscale and Nanoscale Physics · Physics 2013-11-04 T. Tzen Ong , A. M. Black-Schaffer , W. Shen , B. A. Jones

We report the observation and micromagnetic analysis of current-driven magnetization switching in nanoscale ring-shaped magnetic tunnel junctions. When the electric current density exceeds a critical value of the order of $6\times…

Materials Science · Physics 2009-11-13 Hong-Xiang Wei , Jiexuan He , Zhen-Chao Wen , Xiu-Feng Han , Wen-Shan Zhan , Shufeng Zhang

We formulate a theory of current-induced spin torques in inhomogeneous III-V ferromagnetic semiconductors. The carrier spin-3/2 and large spin-orbit interaction, leading to spin non-conservation, introduce significant conceptual differences…

Other Condensed Matter · Physics 2015-05-13 Dimitrie Culcer , M. E. Lucassen , R. A. Duine , R. Winkler

Spin-transfer ferromagnetic resonance (ST-FMR) in symmetric magnetic tunnel junctions (MTJs) with a varied thickness of the MgO tunnel barrier (0.75 nm < $t_{MgO}$ < 1.05 nm) is studied using the spin-torque diode effect. The application of…

A three-dimensional self-consistent spin transport model is developed, which includes both tunnelling transport, as well as metallic transport. Using the spin accumulation computed either side of a tunnel barrier, spin torques are obtained,…

Mesoscale and Nanoscale Physics · Physics 2023-02-01 Serban Lepadatu , Alexey Dobrynin

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

Spin-orbit torque and spin-transfer torque are leading the pathway to the future of spintronic memories. However, both of the mechanisms are suffering from intrinsic limitations. In particular, an external magnetic field is required for…

We study non-equilibrium magneto-transport through a single electron transistor or an impurity. We find that due to spin-flip transitions, generated by the spin-orbit interaction, the spectral density of the tunneling current fluctuations…

Condensed Matter · Physics 2007-05-23 D. Mozyrsky , L. Fedichkin , S. A. Gurvitz , G. P. Berman

We study current-induced switching in magnetic tunnel junctions (MTJs) in the presence of a field-like spin-transfer torque and titled pinned-layer magnetization in the high current limit at finite temperature. We consider both the…

Mesoscale and Nanoscale Physics · Physics 2014-03-21 R. K. Tiwari , M. H. Jhon , N. Ng , D. J. Srolovitz , Chee Kwan Gan

We present spin transfer switching results for MgO based magnetic tunneling junctions (MTJs)with large tunneling magnetoresistance (TMR) ratio of up to 150% and low intrinsic switching current density of 2-3 x 10 MA/cm2. The switching data…

Other Condensed Matter · Physics 2009-11-11 Zhitao Diao , Dmytro Apalkov , Mahendra Pakala , Alex Panchula , Yiming Huai

Current-induced spin-orbit torques provide a versatile tool for switching magnetic devices. In perpendicular magnets, the dampinglike component of the torque is the main driver of magnetization reversal. The degree to which the fieldlike…

The thermal spin-transfer torque (TSTT) is an effect to switch the magnetic free layer in a magnetic tunnel junction by a temperature gradient only. We present ab initio calculations of the TSTT. In particular, we discuss the influence of…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 Christian Heiliger , Michael Czerner

We calculate the spin-transfer torque in Fe/MgO/Fe tunnel junctions and compare the results to those for all-metallic junctions. We show that the spin-transfer torque is interfacial in the ferromagnetic layer to a greater degree than in…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Christian Heiliger , M. D. Stiles

We theoretically study the spin-dependent transport in a ferromagnet/superconductor/ferro-magnet double barrier tunnel junction. The spin-polarized tunneling currents give rise to spin imbalance in the superconductor. The resulting…

Superconductivity · Physics 2009-10-31 Saburo Takahashi , Hiroshi Imamura , Sasamichi Maekawa

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…

The relative contributions of in-plane (damping-like) and out-of-plane (field-like) spin-transfer-torques in the magnetization switching of out-of-plane magnetized magnetic tunnel junctions (pMTJ) has been theoretically analyzed using the…

Mesoscale and Nanoscale Physics · Physics 2015-10-07 A. A. Timopheev , R. Sousa , M. Chshiev , L. D. Buda-Prejbeanu , B. Dieny

We use spin-transfer-driven ferromagnetic resonance (ST-FMR) to measure the spin-transfer torque vector T in MgO-based magnetic tunnel junctions as a function of the offset angle between the magnetic moments of the electrodes and as a…

Other Condensed Matter · Physics 2015-05-13 C. Wang , Y. -T. Cui , J. Z. Sun , J. A. Katine , R. A. Buhrman , D. C. Ralph

Current-induced switching is considered in a magnetic junction. The junction includes pinned and free ferromagnetic layers which work in the regime of the high spin injection. It is shown that in such a regime the exchange magnetization…

Materials Science · Physics 2015-05-13 S. G. Chigarev , E. M. Epshtein , P. E. Zilberman

We present a study of the spin transfer torque oscillator based on CoFeB/MgO/CoFeB asymmetric magnetic tunnel junctions. We observe microwave precession in junctions with different thickness of the free magnetization layer. Taking advantage…

Materials Science · Physics 2013-01-31 Witold Skowroński , Tomasz Stobiecki , Jerzy Wrona , Günter Reiss , Sebastiaan van Dijken

In this work, the effect of electrical coupling on stochastic switching of two in-plane superparamagnetic tunnel junctions (SMTJs) is studied, using experimental measurements as well as simulations. The coupling mechanism relies on the…

Mesoscale and Nanoscale Physics · Physics 2023-07-31 Leo Schnitzspan , Mathias Kläui , Gerhard Jakob