Voltage controlled interfacial magnetism through platinum orbits

Miwa, Shinji; Suzuki, Motohiro; Tsujikawa, Motokazu; Matsuda, K.; Nozaki, Takayuki; Tanaka, Kanako; Tsukahara, Takuya; Nawaoka, Kohei; Goto, Minori; Kotani, Yoshinori; Ohkubo, T.; Bonell, Frédéric; Tamura, E.; Hono, K.; Nakamura, Tetsuya; Shirai, Masamitsu; Yuasa, Shinji; Suzuki, Yoshishige

doi:10.1038/ncomms15848

Cited by 153 publications

(111 citation statements)

References 59 publications

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“…Therefore, in Pt/Co(6 Å)/Pt with PMA, at zero and positive electric field, the anisotropy energy is reduced, favoring the breaking down of the saturated domain into a multidomain state, while a negative electric field increases the anisotropy energy and favors a monodomain state, a result similar to that reported by Mantel et al [30]. We note that the Pt layer is likely to be magnetically polarized through the proximity to the Co layer and that a change in magnetic moment with the electric field may occur [59][60] [61][62] [63], which may also contribute to the change in the magnetic energy.…”

Section: Iii1 Electric Field Control Of Domain Wall Fluctuations Atsupporting

confidence: 75%

Electric field control of magnetism in Si3N4 gated Pt/Co/Pt heterostructures

Vijayakumar

Bracher

Savchenko

et al. 2019

Journal of Applied Physics

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In this work we show the presence of a magnetoelectric coupling in silicon-nitride gated Pt/Co/Pt heterostructures using X-ray photoemission electron microscopy (XPEEM). We observe a change in magnetic anisotropy in the form of domain wall nucleation and a change in the rate of domain wall fluctuation as a function of the applied electric field to the sample. We also observe the coexistence of in-plane and out of plane magnetization in Pt/Co/Pt heterostructures in a region around the spin reorientation transition whose formation is attributed to substrate surface roughness comparable to the film thickness; with such domain configuration, we find that the in-plane magnetization is more sensitive to the applied electric field than out of plane magnetization. Although we find an effective magnetoelectric coupling in our system, the presence of charge defects in the silicon nitride membranes hampers a systematic electrostatic control of the magnetization.

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Section: Iii1 Electric Field Control Of Domain Wall Fluctuations Atsupporting

confidence: 75%

Electric field control of magnetism in Si3N4 gated Pt/Co/Pt heterostructures

Vijayakumar

Bracher

Savchenko

et al. 2019

Journal of Applied Physics

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“…This effect can be induced by purely electronic effects and by chemical or mechanical effects. The physical mechanisms of the purely electronic VCMA effect have been interpreted as the modification of the electronic structure at the interface through charge accumulation/depletion, [21][22][23] an electricfield-induced magnetic dipole 24 or the Rashba effect. 25 Chemical effects, such as a voltage-induced redox reaction, 26 or other electromigration 27 or charge trapping 28 effects can show a substantial VCMA coefficient of the order of a few thousands of fJ Vm − 1 , which is defined as the induced surface anisotropy energy change per unit electric field.…”

Section: Introductionmentioning

confidence: 99%

Highly efficient voltage control of spin and enhanced interfacial perpendicular magnetic anisotropy in iridium-doped Fe/MgO magnetic tunnel junctions

et al. 2017

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Voltage control of spin enables both a zero standby power and ultralow active power consumption in spintronic devices, such as magnetoresistive random-access memory devices. A practical approach to achieve voltage control is the electrical modulation of the spin-orbit interaction at the interface between 3d-transition-ferromagnetic-metal and dielectric layers in a magnetic tunnel junction (MTJ). However, we need to initiate a new guideline for materials design to improve both the voltage-controlled magnetic anisotropy (VCMA) and perpendicular magnetic anisotropy (PMA). Here we report that atomic-scale doping of iridium in an ultrathin Fe layer is highly effective to improving these properties in Fe/MgO-based MTJs. A large interfacial PMA energy, K i,0 , of up to 3.7 mJ m − 2 was obtained, which was 1.8 times greater than that of the pure Fe/MgO interface. Moreover, iridium doping yielded a huge VCMA coefficient (up to 320 fJ Vm − 1 ) as well as high-speed response. First-principles calculations revealed that Ir atoms dispersed within the Fe layer play a considerable role in enhancing K i,0 and the VCMA coefficient. These results demonstrate the efficacy of heavy-metal doping in ferromagnetic layers as an advanced approach to develop high-density voltage-driven spintronic devices. NPG Asia Materials (2017) 9, e451; doi:10.1038/am.2017.204; published online 5 December 2017 INTRODUCTIONSpintronic devices, such as a magnetoresistive random-access memory device using a MgO-based magnetic tunnel junction (MTJ), 1,2 are expected to reduce the standby power of future computing systems by utilizing the non-volatile feature of magnetism. However, one significant challenge emerges from reducing the energy for information writing: magnetization switching. This issue is caused by electriccurrent-based operations of spintronic devices using electric-currentinduced magnetic fields, spin-transfer torque (STT) and spin-orbit torque based on the spin Hall effect rather than the electric-field-based operations presently used for semiconductor devices. For example, recent developments of STT-magnetoresistive random access memory have achieved~100 fJ per bit writing energies, 3 which corresponds to 10 7 k B T, where k B is the Boltzmann constant and T is the temperature (assumed to be 300 K here). In contrast, the energy required for maintaining magnetic information, that is, thermal stability, is between 60 k B T and 100 k B T. This large energy gap between data writing and retention, on the order of 10 5 , mainly originates

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“…Voltage-torque (VT) switching is another attractive method for low power writing, which is based on voltage control of magnetic anisotropy (VCMA) in a thin ferromagnetic film [4,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. The mechanism of the VCMA in a MgO-based MTJ is considered as the combination of the selective electron/hole doping into the d-electron orbitals and the induction of a magnetic dipole moment, which affect the electron spin through the spin-orbit interaction [35][36][37][38][39]. Very recently VT switching with very small write energy of about 6 fJ/bit was demonstrated by Grezes [23] et al and independently by Kanai et al [22].…”

Section: Introductionmentioning

confidence: 99%