Observation of thermally driven field-like spin torque in magnetic tunnel junctions

Abstract

We report the thermally driven giant field-like spin-torque in magnetic tunnel junctions (MTJ) on application of heat current from top to bottom. The field-like term is detected by the shift of the magneto-resistance hysteresis loop applying temperature gradient. We observed that the field-like term depends on the magnetic symmetry of the MTJ. In asymmetric structures, with different ferromagnetic materials for free and fixed layers, the field-like term is greatly enhanced. Our results show that a pure spin current density of the order of 109 A/m2 can be produced by creating a 120 mK temperature difference across 0.9 nm thick MgO tunnelling barrier. Our results will be useful for writing MTJ and domain wall-based memories using thermally driven spin torque.

Sign Reversal of Fieldlike Spin-Orbit Torque in an Ultrathin Cr/Ni Bilayer

“…In this work we experimentally demonstrate that spin-orbit torque is significantly enhanced in Chromium/Nickel (Cr/Ni) bilayer when Cr thickness is below 6 nm. Most interestingly we report unprecedented observation of net field like torque [32] showing opposite sign compared to Oersted field torque. This sign reversal of field like torque could be ascribed to interfacial Rashba coupling.…”

MgO Nanoparticle Modified Anode for Highly Efficient SnO2‐Based Planar Perovskite Solar Cells

“…The plots of −d V /d J versus ( J sc − 1) −1 and linear fitting curves of the PSCs based on the solar cells with and without MgO HBL under illumination are shown in Figure S2 (Supporting Information). The series resistance ( R s ) and ideality factor ( A ) can be calculated from the intercept and slope of the linear fitting results . As a result, the MgO HBL did not influence the R s of the PSCs obviously because the MgO layer was very thin and the electrons can easily tunnel through the MgO layer.…”

Integer, Fractional, and Sideband Injection Locking of a Spintronic Feedback Nano-Oscillator to a Microwave Signal

“…We observe that for low driving fields, sideband locking improves the quality factor of the main peak, whereas for higher driving fields the main peak is suppressed. Further, measurements at two field angles provide some insight into the role of symmetry of oscillation orbit in determining the fractional locking.Nano-oscillators based on the phenomenon of spin-transfer torque (STT) [1][2][3][4][5][6][7] have been the subject of considerable research due to their potential applications in microwave communication devices as well as due to the rich physics involved in their operation. Recently our group demonstrated a spintronic feedback nano-oscillator (SFNO) [8,9] based on the tunneling magnetoresistance (TMR) effect and works without STT.…”