Abstract
We investigated the voltage-controlled magnetic anisotropy (VCMA) in an ultrathin Ir-doped Fe layer with a CoxFe1−x termination layer. The VCMA effect depends on the concentration of the CoxFe1−x alloy, and a large VCMA coefficient, as high as −350 fJ/Vm, was obtained with a Co-rich termination layer. First principles calculations revealed that the increased VCMA effect is due not only to the added Co atoms but also to the Fe and Ir atoms adjacent to the Co atoms. Interface engineering using CoFe termination is also effective for recovering the tunneling magnetoresistance while maintaining a high VCMA effect. The developed structure is applicable for voltage-controlled magnetoresistive devices.
Highlights
Takayuki Nozaki,1 Masaki Endo,2 Masahito Tsujikawa,3 Tatsuya Yamamoto,1 Tomohiro Nozaki,1 Makoto Konoto,1 Hiroyuki Ohmori,2 Yutaka Higo,2 Hitoshi Kubota,1 Akio Fukushima,1 Masanori Hosomi,2 Masafumi Shirai,3 Yoshishige Suzuki,1,4 and Shinji Yuasa1
Excitation of high speed spin dynamics by the voltage-controlled magnetic anisotropy (VCMA) effect led to demonstrations of ferromagnetic resonance excitation10,11 and precession-mediated dynamic magnetization switching in MgO-based magnetic tunnel junction (MTJ) solely by the application of a voltage pulse
Of the free layer is dominated by the magnetic anisotropy at the interface between the free and dielectric layers, the required effective perpendicular magnetic anisotropy (PMA) energy is estimated to be 0.2–0.5 mJ/m2 for cache memory and 0.5–2.0 mJ/m2 for main memory applications. To eliminate these PMA energies, VCMA coefficients of about 200–500 f J/Vm and 500–2000 f J/Vm are demanded for each specification, assuming scitation.org/journal/apm a switching electric field of 1 V/nm, a free layer thickness of 1 nm, and a thermal stability factor ranging from 30 to 80
Summary
Takayuki Nozaki,1 Masaki Endo,2 Masahito Tsujikawa,3 Tatsuya Yamamoto,1 Tomohiro Nozaki,1 Makoto Konoto,1 Hiroyuki Ohmori,2 Yutaka Higo,2 Hitoshi Kubota,1 Akio Fukushima,1 Masanori Hosomi,2 Masafumi Shirai,3 Yoshishige Suzuki,1,4 and Shinji Yuasa1. To eliminate these PMA energies, VCMA coefficients of about 200–500 f J/Vm and 500–2000 f J/Vm are demanded for each specification, assuming scitation.org/journal/apm a switching electric field of 1 V/nm, a free layer thickness of 1 nm, and a thermal stability factor ranging from 30 to 80.
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