Enhancement of two-magnon scattering induced by a randomly distributed antiferromagnetic exchange field

Sakimura, Hiroto; Asami, Akio; Harumoto, Takashi; Nakamura, Yoshio; Shi, Ji; Ando, Kotoji

doi:10.1103/physrevb.98.144406

Cited by 15 publications

(12 citation statements)

References 49 publications

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“…oxides (CoO, NiO, and α-Fe 2 O 3 ) become antiferromagnetic (AF). If it has an antiferromagnetic order, the angular momentum can be dissipated through the transfer of magnons 28,29 (or spin fluctuation) to the antiferromagnetic oxides.…”

Section: Resultsmentioning

confidence: 99%

“…We speculate that the enhanced α originates from the antiferromagnetic nature of interfacial oxides for two reasons: First, below the Néel temperature ( T N ), the interfacial magnetic oxides (CoO, NiO, and α-Fe 2 O 3 ) become antiferromagnetic (AF). If it has an antiferromagnetic order, the angular momentum can be dissipated through the transfer of magnons , (or spin fluctuation) to the antiferromagnetic oxides.…”

Section: Results and Discussionmentioning

confidence: 99%

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Effects of Interfacial Oxidization on Magnetic Damping and Spin–Orbit Torques

Lee

Jeong

Yun

et al. 2021

ACS Appl. Mater. Interfaces

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We investigate the effects of interfacial oxidation on the perpendicular magnetic anisotropy, magnetic damping, and spin−orbit torques in heavy-metal (Pt)/ferromagnet (Co or NiFe)/capping (MgO/Ta, HfO x , or TaN) structures. At room temperature, the capping materials influence the effective surface magnetic anisotropy energy density, which is associated with the formation of interfacial magnetic oxides. The magnetic damping parameter of Co is considerably influenced by the capping material (especially MgO) while that of NiFe is not. This is possibly due to extra magnetic damping via spin-pumping process across the Co/CoO interface and incoherent magnon generation (spin fluctuation) developed in the antiferromagnetic CoO. It is also observed that both antidamping and field-like spin−orbit torque efficiencies vary with the capping material in the thickness ranges we examined. Our results reveal the crucial role of interfacial oxides on the perpendicular magnetic anisotropy, magnetic damping, and spin−orbit torques.

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Section: Resultsmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Effects of Interfacial Oxidization on Magnetic Damping and Spin–Orbit Torques

Lee

Jeong

Yun

et al. 2021

ACS Appl. Mater. Interfaces

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“…Although the spin mixing conductance is typically determined by measuring the magnetic damping, recent studies have suggested that extraction of the parameter requires a careful determination of the two-magnon scattering, as well as the interface spin memory loss, which has previously been neglected. 136 , 137 ) This suggests that explorating the generation and manipulation of spin-orbit torques with further careful experiments will provide essential information for a fundamental understanding of spin-orbit physics in solid-state devices.…”

Section: Discussionmentioning

confidence: 99%

Generation and manipulation of current-induced spin-orbit torques

Ando

2021

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

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“…We note that in the Ni 81 Fe 19 /NiO/Pt trilayers, the NiO layer is polycrystalline, as evidenced by the X-ray diffractometry [32]. This suggests that the two-magnon scattering can be induced by the random fluctuation of uniaxial anisotropy due to randomly oriented exchange bias fields [35]. In fact, the measured θ H dependence of ∆H is well reproduced by a calculation which takes into account the additional damping due to the two-magnon scattering as shown in Fig.…”

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confidence: 98%

“…3(a) [28,35] [for details, see [32]]. In the Ni 81 Fe 19 /NiO/Pt trilayers, the random fluctuation of uniaxial anisotropy due to the randomly oriented exchange bias increases with d NiO [35]; although the surface roughness of the NiO layer is almost unchanged with d NiO [32], the amplitude of the two-magnon scattering C TMS increases with d NiO , which is reminiscent of the increased suppression of V ISHE with d NiO shown in Fig. 2(c).…”

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confidence: 99%

Intrinsic spin decay length in an antiferromagnetic insulator

Sakimura

Asami

Hayashi

et al. 2019

Phys. Rev. Research

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We report intrinsic spin decay length of an antiferromagnetic insulator. We found that at an antiferromagnetic/ferromagnetic interface, a spin current generated by spin pumping is strongly suppressed by two-magnon scattering. By eliminating the two-magnon contribution, we discovered that the characteristic length of spin decay in NiO changes by two-orders of magnitude through the paramagnetic to antiferromagnetic transition. The spin decay length in the antiferromagnetic state is longer than 100 nm, which is an order of magnitude longer than previously believed. These results provide a crucial piece of information for the fundamental understanding of the physics of spin transport.Spintronics relies on the transport of spins in condensed matter [1][2][3]. Spin transport has been investigated in a variety of materials, including metals, semiconductors, and insulators. In metals and semiconductors, spins are transported by the diffusion of conduction electrons [3]. In contrast, in magnetically-ordered materials, spins can be transported even in the absence of conduction electrons; spins are carried by the elementary excitations of magnetic moments, magnons [4]. The magnonic spin current in insulators is of particular recent interest because this sets a new direction for experimental and theoretical studies of the physics of spin transport [5,6].Antiferromagnetic insulators is a new class of materials for spin transport [7][8][9]. This class of materials potentially entails a number of advantages as compared to ferromagnets: antiferromagnets are robust against external magnetic fields, produce no stray fields, and display ultrafast dynamics. Since the first observation of the transmission of spins through an antiferromagnetic insulator NiO [10-12], intense experimental and theoretical efforts have been invested in unraveling the physics of the spin transport in antiferromagnetic insulators [10][11][12][13][14][15][16][17][18][19][20][21][22]. In antiferromagnetic insulators, the spindecay length is known to be typically limited to only a few nanometers [9], although theories predict longdistance spin transport in antiferromagnets [23]. This is in stark contrast to the situation for ferromagnetic insulators, where long-distance spin propagation has been observed [4,5].In this Letter, we reveal the intrinsic character of magnonic spin transport in an antiferromagnetic insulator. We found that, in the conventional spininjector/antiferromagnetic-insulator/spin-detector structure, the spin-transmission signal is strongly suppressed by two-magnon scattering. By eliminating the twomagnon contribution in the spin-transmission signal, we show that the spin decay length of a prototypical antiferromagnetic insulator NiO changes by two-orders of magnitude through the paramagnetic to antiferromagnetic transition. This result shows that the intrinsic spin decay length of the antiferromagnetic NiO is an order of magnitude longer than the previously believed, provid-μ -1 0 1 -50 0 50 0 5 10 0 nm 4.1 nm dI(H)/dH (arb. unit) H -H res ...

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Enhancement of two-magnon scattering induced by a randomly distributed antiferromagnetic exchange field

Cited by 15 publications

References 49 publications

Effects of Interfacial Oxidization on Magnetic Damping and Spin–Orbit Torques

Effects of Interfacial Oxidization on Magnetic Damping and Spin–Orbit Torques

Generation and manipulation of current-induced spin-orbit torques

Intrinsic spin decay length in an antiferromagnetic insulator

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