Quantifying interface and bulk contributions to spin–orbit torque in magnetic bilayers

Fan, Xin; Celik, Halise; Wu, Jun; Ni, Chaoying; Lee, Kyung Jin; Lorenz, Virginia O.; Xiao, John Q.

doi:10.1038/ncomms4042

Cited by 306 publications

(264 citation statements)

References 30 publications

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“…It was also recently demonstrated that both collinear [38] and non-collinear AFMs [33,[39][40][41][42] can generate a large SOT on FMs in AFM/FM heterostructures. While the origin of such a torque is not clear [41] it is known that in heavy metal/FM heterostructures, the SHE plays an important role [43,44]. Here we show, that apart from the conventional SHE, which was theoretically studied in Ref.…”

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confidence: 46%

Spin-Polarized Current in Noncollinear Antiferromagnets

et al. 2017

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Noncollinear antiferromagnets, such as Mn3Sn and Mn3Ir, were recently shown to be analogous to ferromagnets in that they have a large anomalous Hall effect. Here we show that these materials are similar to ferromagnets in another aspect: the charge current in these materials is spin-polarized. In addition, we show that the same mechanism that leads to the spin-polarized current also leads to a transversal spin current, which has a distinct symmetry and origin from the conventional spin Hall effect. We illustrate the existence of the spin-polarized current and the transversal spin current by performing ab initio microscopic calculations and by analyzing the symmetry. Based on the spinpolarized current we propose an antiferromagnetic tunneling junction, analogous in functionality to the magnetic tunneling junction.Introduction. Spintronics is a field that studies phenomena in which both spin and charge degree of electron play an important role. Many of the key spintronics effects are based upon the existence of spin currents. Two main types of spin currents are utilized: the spin-polarized currents in ferromagnets (FMs) and the spin currents due to the spin Hall effect (SHE) which are transveral to the charge current and appear even in non-magnetic materials. The most important effects that originate from the spin-polarized currents in FMs are the giant and the tunneling magnetoresistance effects (GMR and TMR) [1][2][3] and the spin-transfer torque (STT) [4,5]. These effects are utilized in magnetic tunneling junctions (MTJs), which form the basic building block of a new type of solid state memory, the magnetic random access memory (MRAM) [6]. This memory is non-volatite and has speed and density comparable to the widely used dynamic random access memory. The SHE on the other hand is responsible (though other effects can contribute) for the spin-orbit torque (SOT) [7,8] in multilayer heterostructures, which can be used for efficient and fast switching of FM layers. The SOT is now also being explored for use in MRAMs [9,10].While spintronics has traditionally focused on FM and non-magnetic materials, in the past few years also antiferromagnetic (AFM) materials have attracted a considerable interest. AFMs offer some unique advantages compared to FMs, but are much less explored (see reviews [11][12][13]). AFMs have a very fast dynamics, which allows for switching on ps timescale [14][15][16]. Furthermore, there exists a wide range of AFM materials, including many insulators and semiconductors, multiferroics [17] and superconductors [18]. Utilizing (and also studying) AFMs is difficult, largely because the magnetic order in AFMs is hard to detect and to manipulate. Recently, electrical detection [19][20][21][22][23] and manipulation of the AFM order has been demonstrated [23,24], however, both detection and manipulation still remain challenging from a practical point of view.

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confidence: 46%

Spin-Polarized Current in Noncollinear Antiferromagnets

et al. 2017

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“…1(b)). Second order PHE measurements were carried out to quantify the spin current induced effective field in both FeMn/Pt bilayers and NiFe/FeMn/Pt trilayers 10,12 the schematic of Fig. 2(a), when a charge current j c flows in x-direction, a spin current j s is generated In addition to Hall bars, coupon films have also been prepared for X-ray diffraction and magnetic measurements.…”

Section: Methodsmentioning

confidence: 99%

“…7(a). For a better linear approximation, the data at low fields were excluded and only the data at fields above ±1 kOe were used for the fitting 10 . H I can be calculated from the slope k by using the relation H I = 2kH bias .…”

Section: Phe Measurements Of Femn/pt Bilayersmentioning

confidence: 99%

“…H I can be calculated from the slope k by using the relation H I = 2kH bias . The offset between the fitting lines at positive and negative region is understood to be caused by either H DL or the thermal effect 10,12 . The small amplitude of the offset confirms again that the contributions from both effects are small in the PHE signals obtained from the FeMn/Pt bilayers.…”

Section: Phe Measurements Of Femn/pt Bilayersmentioning

confidence: 99%

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Fieldlike spin-orbit torque in ultrathin polycrystalline FeMn films

Yang

Zhang

et al. 2016

Phys. Rev. B

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“…Values of DL j ξ for Pt have been reported spanning the range 0.06 -0.12 [19,[27][28][29], depending on the FM/Pt interface [31], and are usually accompanied by a relatively small field-like (FL) torque efficiency whose magnitude and sign vary with the interface, FM magnetic anisotropy and temperature [29,[32][33][34][35][36]. From an analysis of SBF based on a spin diffusion model [24,25] is a well-known phenomenon due to strong diffusive scattering at a Pt surface [48,[53][54][55][56][57].…”

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confidence: 99%