Spin transfer torque on magnetic insulators

Jia, Xingtao; Li, Kai; Xia, Ke; Bauer, G.

doi:10.1209/0295-5075/96/17005

Cited by 210 publications

(218 citation statements)

References 32 publications

Supporting

Mentioning

182

Contrasting

Unclassified

Order By: Relevance

“…A previous study shows that at the Ag/YIG interface, the enhanced local magnetic exchange field at the interface enhances G r [29], which can be interpreted as enhanced s− d coupling in our calculation and is fairly consistent with the {q − , k 0↓ } > q + situation. In the Stoner limit {Γ, |µ 0 |} ≪ {ǫ, V 0 − ǫ}, the field-like component dominates, in good agreement with Ref.…”

supporting

confidence: 90%

Minimal Model of Spin-Transfer Torque and Spin Pumping Caused by the Spin Hall Effect

et al. 2015

View full text Add to dashboard Cite

In the normal metal/ferromagnetic insulator bilayer (such as Pt/Y3Fe5O12) and the normal metal/ferromagnetic metal/oxide trilayer (such as Pt/Co/AlOx) where spin injection and ejection are achieved by the spin Hall effect in the normal metal, we propose a minimal model based on quantum tunneling of spins to explain the spin-transfer torque and spin pumping caused by the spin Hall effect. The ratio of their damping-like to field-like component depends on the tunneling wave function that is strongly influenced by generic material properties such as interface s − d coupling, insulating gap, and layer thickness, yet the spin relaxation plays a minor role. The quantified result renders our minimal model an inexpensive tool for searching for appropriate materials. [6,7]. Unlike in metallic heterostructures, the usual way of spin injection by using a spin-polarized charge current in the currentperpendicular-to-plane (CPP) geometry is difficult in NM/FMI because the insulating FMI impedes the charge current. Instead, the spin injection in this system is done by using the spin Hall effect (SHE) in the NM, which in the current-in-plane (CIP) geometry injects a pure spin current into the FMI to cause STT. In the reciprocal process, SHE converts the pure spin current generated from spin pumping into electric signals. Despite pointing at promising applications in magnetic memory devices, the microscopic mechanism concerning how the pure spin current tunnels into an insulator to cause STT and spin pumping remains unclear, especially if spin relaxation plays a crucial role as in metallic heterostructures [1].

show abstract

supporting

confidence: 90%

Minimal Model of Spin-Transfer Torque and Spin Pumping Caused by the Spin Hall Effect

et al. 2015

View full text Add to dashboard Cite

show abstract

“…In most of the parameter space, the torque is dominated by field-like component |G r /G i | < 1 throughout the whole range of l F I . Only when the magnitude of s − d coupling is large compared to the insulating gap (V 0 − ǫ F )/ǫ F is the torque dominated by the damping-like component |G r /G i | > 1, consistent with that found previously 26 and also in accordance with the result from first principle calculation 23 . The magnitude of G r,i generally increases with the s − d coupling, yet more dramatically for G r .…”

Section: A Interface Spin Currentsupporting

confidence: 91%

Effect of quantum tunneling on spin Hall magnetoresistance

Chen

Sigrist

et al. 2016

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

We present a formalism that simultaneously incorporates the effect of quantum tunneling and spin diffusion on spin Hall magnetoresistance observed in normal metal/ferromagnetic insulator bilayers (such as Pt/Y3Fe5O12) and normal metal/ferromagnetic metal bilayers (such as Pt/Co), in which the angle of magnetization influences the magnetoresistance of the normal metal. In the normal metal side the spin diffusion is known to affect the landscape of the spin accumulation caused by spin Hall effect and subsequently the magnetoresistance, while on the ferromagnet side the quantum tunneling effect is detrimental to the interface spin current which also affects the spin accumulation. The influence of generic material properties such as spin diffusion length, layer thickness, interface coupling, and insulating gap can be quantified in a unified manner, and experiments that reveal the quantum feature of the magnetoresistance are suggested.

show abstract

“…1(a)]. However, when s and M are noncollinear, part of the spin current will be absorbed by M via a spin-transfer torque [30][31][32], leading to maximum spin absorption for perpendicular M and s [ Fig. 1(b)].…”

mentioning

confidence: 99%

“…Equation (3) shows that two quantities renormalize the spin-diffusion length: the spinmixing conductance by means of the real term 2ρG r λ 2 /t, and the imaginary Hanle term i(λ/λ m ) 2 originating from the applied field. While the former leads to a reduction of λ due to the torque exerted by the NM/FMI interface to the spins [30,32], the latter causes, in addition, the precession of the spins when the s and H are noncollinear [40].…”

mentioning

confidence: 99%

Modulation of pure spin currents with a ferromagnetic insulator

et al. 2015

View full text Add to dashboard Cite

We propose and demonstrate spin manipulation by magnetically controlled modulation of pure spin currents in cobalt/copper lateral spin valves, fabricated on top of the magnetic insulator Y 3 Fe 5 O 12 (YIG). The direction of the YIG magnetization can be controlled by a small magnetic field. We observe a clear modulation of the nonlocal resistance as a function of the orientation of the YIG magnetization with respect to the polarization of the spin current. Such a modulation can only be explained by assuming a finite spin-mixing conductance at the Cu/YIG interface, as it follows from the solution of the spin-diffusion equation Spintronics is a rapidly growing field that aims at using and manipulating not only the charge, but also the spin of the electron, which could lead to faster data processing, nonvolatility, and lower electrical power consumption as compared to conventional electronics [1]. Sophisticated applications such as hard-disk read heads and magnetic random access memory (MRAM) have been introduced in the last two decades.Further progress could be achieved with pure spin currents, which are an essential ingredient in an envisioned spin-only circuit that would integrate logics and memory [2]. The most basic unit in such a concept is the spin analog to the transistor, in which the manipulation of pure spin currents is crucial. The original proposal by Datta and Das [3], which is also applicable to pure spin currents [4], suggested a spin manipulation that would arise from the spin precession due to the spin-orbit interaction modulated by an electric field (Rashba coupling). However, a fundamental limitation appears here, because the best materials for spin transport are those showing the lowest spin-orbit interaction and, therefore, there has been no success in electrically manipulating the spins and propagating them at the same environment, with few exceptions [4].Alternative ways to control pure spin currents are thus desirable. One could take advantage of the spin-mixing conductance concept [5,6] at nonmagnetic metal (NM)/ferromagnetic insulator (FMI) interfaces, which governs the interaction between the spin currents present at the NM and the magnetization of the FMI. This concept is the basis of new spindependent phenomena, including spin pumping [6][7][8][9][10][11][12], spin Seebeck effect [6,13], and spin Hall magnetoresistance (SMR) [6,[14][15][16][17][18]. In these cases, a NM with large spin-orbit coupling is required to convert the involved spin currents into charge currents via the inverse spin Hall effect [19].In this Rapid Communication, we demonstrate an alternative way of modulating pure spin currents based on a magnetic, instead of electric, gating. To that end, we use lateral spin valves (LSVs). These devices allow an electrical injection and detection of pure spin currents in a NM channel by using * f.casanova@nanogune.eu ferromagnetic (FM) electrodes in a nonlocal configuration [20][21][22][23][24][25][26][27][28][29]. The LSVs have been fabricated on top of a FMI, in order to enab...

show abstract

Spin transfer torque on magnetic insulators

Cited by 210 publications

References 32 publications

Minimal Model of Spin-Transfer Torque and Spin Pumping Caused by the Spin Hall Effect

Minimal Model of Spin-Transfer Torque and Spin Pumping Caused by the Spin Hall Effect

Effect of quantum tunneling on spin Hall magnetoresistance

Modulation of pure spin currents with a ferromagnetic insulator

Contact Info

Product

Resources

About