Magnetoelectric Effect in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions
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Magnetoelectric Effect in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions I. Yu. Pashen’kina, *, M. V. Sapozhnikova, b, N. S. Guseva, V. V. Rogova, D. A. Tatarskiia, b, A. A. Fraermana, and M. N. Volochaevc a
Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhny Novgorod, 603950 Russia b Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603950 Russia c Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036 Russia *e-mail: [email protected] Received April 27, 2020; revised May 1, 2020; accepted May 1, 2020
The possibility of electrical control of the interlayer exchange interaction in CoFeB/MgO/CoFeB tunnel junctions exhibiting magnetoresistance of ~200% is studied. It is shown that the increase in the applied voltage from 50 mV to 1.25 V leads to a shift of the magnetization curve of the free layer by 10 Oe at a current density of ~103 A/cm2. The discovered effect can be used in the development of energy-efficient random access memory. DOI: 10.1134/S0021364020120115
One of the most urgent practically significant problems of spin electronics is to control the magnetic state of nanosystems by the electric field (magnetoelectric effect), i.e., without the application of highdensity currents. The use of the magnetoelectric effect ensures the high recording density and energy efficiency of magnetoresistive random access memory (MRAM). The MRAM element is a tunnel magnetoresistive (TMR) junction, the logical state (resistance) of which is determined by the mutual orientation of the magnetizations of the free (soft magnetic) and fixed (hard magnetic) layers. Recording information into a cell involves the magnetization reversal of its free layer, which is a nontrivial task. In the first commercially available MRAMs, switching was performed by the magnetic fields of the recording current buses [1, 2]. When moving to the nanoscale, this approach turns out to be extremely inefficient because of a high heat release and the impossibility of localizing magnetic fields. Currently, the recording process is based on the application of spin polarized currents of very high densities (~106 A/cm2) to a system [3, 4], inevitably leading to significant energy loss. Magnetization reversal caused by the dependence of magnetic anisotropy on the applied voltage [5, 6] does not require high currents, but in view of the quadratic dependence of the effect on magnetization, the deterministic switching is possible only in the dynamic mode, which imposes strict requirements on the duration and shape of voltage pulses. The controlled anisotropy effect is also used to assist magnetization reversal by a spinpolarized current [7], but the switching barrier
decreases only in one direction (e.g., from 0 to 1) because the effect is an even function of the voltage. The dependence of the interlayer exchange interaction on the voltage [8] applied to the TMR junction allows deterministic switching at a relatively low current density passing through the system. This effe
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