Giant Spin Pumping and Inverse Spin Hall Effect in the Presence of Surface and Bulk Spin−Orbit Coupling of Topological Insulator Bi<sub>2</sub>Se<sub>3</sub>

Jamali, Mahdi; Lee, Joon Sue; Jeong, Jong Seok; Mahfouzi, Farzad; Lv, Yang; Zhao, Zhengyang; Nikolić, Branislav K.; Mkhoyan, K. Andre; Samarth, N.; Wang, Jian Ping

doi:10.1021/acs.nanolett.5b03274

Cited by 284 publications

(283 citation statements)

References 54 publications

Supporting

Mentioning

242

Contrasting

Unclassified

Order By: Relevance

“…15,16,18,19 Moreover, the performance of spin current generation in the STO/LAO heterostructure is similar or even better than the emerging topological insulator Bi2Se3 with SOT efficiency of ~0.43-3.5. 22,25,26 Our observation further confirms the previous report, which shows a strong current induced Rashba effective field HR with the value of ~1.76 T for a charge current density of JC = 10 5 A/cm 2 . 8 In our STO/LAO/CFB device, there is a ~3.1-nm thin LAO insulting layer separating the STO/LAO spin source and CFB magnetic layer, which is different from previous cases with a direct contact of the heavy metal (or topological insulator) with a ferromagnetic layer.…”

supporting

confidence: 91%

Room-Temperature Giant Charge-to-Spin Conversion at the SrTiO₃–LaAlO₃ Oxide Interface

et al. 2017

View full text Add to dashboard Cite

Two-dimensional electron gas (2DEG) formed at the interface between SrTiO3 (STO) and LaAlO3 (LAO) insulating layer is supposed to possess strong Rashba spin-orbit coupling. To date, the inverse Edelstein effect (i.e. spin-to-charge conversion) in the 2DEG layer is reported. However, the direct effect of charge-to-spin conversion, an essential ingredient for spintronic devices in a current induced spin-orbit torque scheme, has not been demonstrated yet.Here we show, for the first time, a highly efficient spin generation with the efficiency of ~6.3 in the STO/LAO/CoFeB structure at room temperature by using spin torque ferromagnetic resonance.In addition, we suggest that the spin transmission through the LAO layer at high temperature range is attributed to the inelastic tunneling via localized states in the LAO band gap. Our findings may lead to potential applications in the oxide insulator based spintronic devices.

show abstract

supporting

confidence: 91%

Room-Temperature Giant Charge-to-Spin Conversion at the SrTiO₃–LaAlO₃ Oxide Interface

et al. 2017

View full text Add to dashboard Cite

show abstract

“…From Eqs. (3) and (4) we obtain ↑↓ =13.3 nm -2 , in the range of reported values for interfacial systems 18,25 , and js=8.4 10 6 A.m -2 .G -2 . Combining this value with the measured twodimensional charge current yields the spin-to-charge current conversion efficiency parameterized by the inverse Edelstein length = 2 / .…”

supporting

confidence: 67%

Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces

Lesne¹,

Fu²,

Oyarzún³

et al. 2016

Nature Mater

463

432

View full text Add to dashboard Cite

The spin-orbit interaction couples the electrons' motion to their spin. Accordingly, passing a current in a material with strong spin-orbit coupling generates a transverse spin current (spin Hall effect, SHE) and vice-versa (inverse spin Hall effect, ISHE) 1-3 . The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronics functionalities 4,5 and devices, some of which do not require any ferromagnetic material 6 . However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronics hetero-and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism  the Rashba effect 7  in the oxide two-dimensional electron system (2DES) LaAlO3/SrTiO3 to achieve spin-to-charge conversion with unprecedented efficiency. Through spin-pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES. Perovskite oxide materials possess a broad range of functionalities, some of which can be very appealing for spintronics. This includes half-metallicity in mixed-valence manganites  that can be used to produce giant tunnel magnetoresistance 8  or multiferroicity  through which magnetization direction can be electrically controlled at low power 9 . The recent years have seen the emergence of novel spintronics effects based on the generation and control of pure spin currents through spin-orbit effects in semiconducting and metallic systems 1-3 . However, despite a renewal of interest for 4d and 5d transition metal perovksites 10 , spin-orbit effects remained largely unexplored in oxide spintronics.An emerging direction in oxide research aims at discovering novel electronic phases at interfaces between two oxide materials 11 . A well-known example is the LaAlO3/SrTiO3 system: while both LaAlO3 (LAO) and SrTiO3 (STO) are wide bandgap semiconductors, a high-mobility two-dimensional electron system (2DES) forms at their interface 12 if the LAO thickness is at least 4 unit-cells (uc). Interestingly, LAO/STO possesses several remarkable extra functionalities including a gate-tuneable Rashba effect 13,14 , which makes it particularly appealing for spintronics.The Rashba effect is a manifestation of the spin-orbit interaction (SOI) in solids, where spin degeneracy associated with the spatial inversion symmetry is lifted due to a symmetry-breaking electric field normal to an heterointerface 15 . In a Rashba 2DES, the flow of a charge current results in the creation of a nonzero spin accumulation 16,17 coming from uncompensated spin-textured Fermi surfaces. Recently, the converse effect so-called inverse Edelstein effect (IEE)  that is a spin-to-charge conversion through SOI  was discovered a...

show abstract

“…The key feature for connecting experimentally observed SOT and other related phenomena in F/TI heterostructures (such as spin-to-charge conversion [28,35,55]) to theoretical predictions is their dependence [2,24] on the magnetization direction. The antidamping-like SOT predicted in our study exhibits complex angular dependence, including also "nonperturbative" change with the magnetization direction in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…For example, TI samples used in these experiments are often unintentionally doped, so that bulk charge carriers can generate anti-damping-like SOT via rather large [24] SHE (but not sufficient to explain all reported values [14,15]). The simplistic picture [14], in which electrons spin polarized by the EE diffuse into the F overlayer [14] to deposit spin angular momentum within it, cannot operate in technologically relevant F overlayers of 1-nm thickness [16] or explain complex angular dependence [2,15,25] typically observed for SOT.…”

Section: Introductionmentioning

confidence: 99%

Antidamping spin-orbit torque driven by spin-flip reflection mechanism on the surface of a topological insulator: A time-dependent nonequilibrium Green function approach

2016

Self Cite

View full text Add to dashboard Cite

Motivated by recent experiments observing spin-orbit torque (SOT) acting on the magnetization m of a ferromagnetic (F) overlayer on the surface of a three-dimensional topological insulator (TI), we investigate the origin of the SOT and the magnetization dynamics in such systems. We predict that lateral F/TI bilayers of finite length, sandwiched between two normal metal leads, will generate a large anti-damping-like SOT per very low charge current injected parallel to the interface. The large values of anti-damping-like SOT are spatially localized around the transverse edges of the F overlayer. Our analysis is based on adiabatic expansion (to first order in ∂ m/∂t) of time-dependent nonequilibrium Green functions (NEGFs), describing electrons pushed out of equilibrium both by the applied bias voltage and by the slow variation of a classical degree of freedom [such as m(t)]. From it we extract formulas for spin torque and charge pumping, which show that they are reciprocal effects to each other, as well as Gilbert damping in the presence of SO coupling. The NEGF-based formula for SOT naturally splits into four components, determined by their behavior (even or odd) under the time and bias voltage reversal. Their complex angular dependence is delineated and employed within Landau-Lifshitz-Gilbert simulations of magnetization dynamics in order to demonstrate capability of the predicted SOT to efficiently switch m of a perpendicularly magnetized F overlayer.

show abstract

Giant Spin Pumping and Inverse Spin Hall Effect in the Presence of Surface and Bulk Spin−Orbit Coupling of Topological Insulator Bi₂Se₃

Cited by 284 publications

References 54 publications

Room-Temperature Giant Charge-to-Spin Conversion at the SrTiO₃–LaAlO₃ Oxide Interface

Room-Temperature Giant Charge-to-Spin Conversion at the SrTiO₃–LaAlO₃ Oxide Interface

Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces

Antidamping spin-orbit torque driven by spin-flip reflection mechanism on the surface of a topological insulator: A time-dependent nonequilibrium Green function approach

Contact Info

Product

Resources

About

Giant Spin Pumping and Inverse Spin Hall Effect in the Presence of Surface and Bulk Spin−Orbit Coupling of Topological Insulator Bi2Se3

Cited by 284 publications

References 54 publications

Room-Temperature Giant Charge-to-Spin Conversion at the SrTiO3–LaAlO3 Oxide Interface

Room-Temperature Giant Charge-to-Spin Conversion at the SrTiO3–LaAlO3 Oxide Interface

Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces

Antidamping spin-orbit torque driven by spin-flip reflection mechanism on the surface of a topological insulator: A time-dependent nonequilibrium Green function approach

Contact Info

Product

Resources

About

Giant Spin Pumping and Inverse Spin Hall Effect in the Presence of Surface and Bulk Spin−Orbit Coupling of Topological Insulator Bi₂Se₃

Room-Temperature Giant Charge-to-Spin Conversion at the SrTiO₃–LaAlO₃ Oxide Interface

Room-Temperature Giant Charge-to-Spin Conversion at the SrTiO₃–LaAlO₃ Oxide Interface