One-dimensional spinon spin currents

Hirobe, Daichi; Sato, Masahiro; Shiomi, Yuki; Uchida, K.; Iguchi, Ryo; Koike, Yasuhiro; Maekawa, Sadamichi; Saitoh, Eiji

doi:10.1038/nphys3895

Cited by 151 publications

(123 citation statements)

References 43 publications

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“…Hence, quantum antiferromagnets host exotic, strongly correlated excitations, and because of these, they have been the objects of intense research in condensed matter physics for more than 60 years (Giamarchi, 2003;Balents, 2010). Although this topic is beyond the scope of the present review, we believe that the recent observation of a spinon-mediated spin Seebeck effect in the Sr 2 CuO 3 onedimensional antiferromagnet might bridge the gap between antiferromagnetic spintronics and frustrated systems (Hirobe et al, 2016).…”

Section: Insulatormentioning

confidence: 96%

Antiferromagnetic spintronics

et al. 2018

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Antiferromagnetic materials could represent the future of spintronic applications thanks to the numerous interesting features they combine: they are robust against perturbation due to magnetic fields, produce no stray fields, display ultrafast dynamics, and are capable of generating large magnetotransport effects. Intense research efforts over the past decade have been invested in unraveling spin transport properties in antiferromagnetic materials. Whether spin transport can be used to drive the antiferromagnetic order and how subsequent variations can be detected are some of the thrilling challenges currently being addressed. Antiferromagnetic spintronics started out with studies on spin transfer and has undergone a definite revival in the last few years with the publication of pioneering articles on the use of spin-orbit interactions in antiferromagnets. This paradigm shift offers possibilities for radically new concepts for spin manipulation in electronics. Central to these endeavors are the need for predictive models, relevant disruptive materials, and new experimental designs. This paper reviews the most prominent spintronic effects described based on theoretical and experimental analysis of antiferromagnetic materials. It also details some of the remaining bottlenecks and suggests possible avenues for future research. This review covers both spin-transfer-related effects, such as spin-transfer torque, spin penetration length, domain-wall motion, and "magnetization" dynamics, and spin-orbit related phenomena, such as (tunnel) anisotropic magnetoresistance, spin Hall, and inverse spin galvanic effects. Effects related to spin caloritronics, such as the spin Seebeck effect, are linked to the transport of magnons in antiferromagnets. The propagation of spin waves and spin superfluids in antiferromagnets is also covered.

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Section: Insulatormentioning

confidence: 96%

Antiferromagnetic spintronics

et al. 2018

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“…From these measurements, the strength of the Kitaev couplings was estimated to be about 100 K. In addition, measurement of the specific heat 21 suggested magnetic-entropy release at about 90 K, which appears consistent with the theoretical prediction for itinerant Majorana fermions in the Kitaev spin liquid 12,36 . Various experimental techniques have been applied to α-RuCl 3 ; however, its transport properties have not been well explored despite the fact that transport experiments are often used for detecting signatures of spin liquid states and their fractionalized excitations [38][39][40][41] . In this paper, we experimentally study the thermal conductivity κ in α-RuCl 3 .…”

Section: Introductionmentioning

confidence: 99%

Magnetic thermal conductivity far above the Néel temperature in the Kitaev-magnet candidate α−RuCl3

Hirobe¹,

Sato²,

Shiomi³

et al. 2017

Phys. Rev. B

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We have investigated the longitudinal thermal conductivity of α-RuCl3, the magnetic state of which is considered to be proximate to a Kitaev honeycomb model, along with the spin susceptibility and magnetic specific heat. We found that the temperature dependence of the thermal conductivity exhibits an additional peak around 100 K, which is well above the phonon peak temperature (∼ 50 K). The higher-temperature peak position is comparable to the temperature scale of the Kitaev couplings rather than the Néel temperatures below 15 K. The additional heat conduction was observed for all five samples used in this study, and was found to be rather immune to a structural phase transition of α-RuCl3, which suggests its different origin from phonons. Combined with experimental results of the magnetic specific heat, our transport measurement suggests strongly that the higher-temperature peak in the thermal conductivity is attributed to itinerant spin excitations associated with the Kitaev couplings of α-RuCl3. A kinetic approximation of the magnetic thermal conductivity yields a mean free path of ∼ 20 nm at 100 K, which is well longer than the nearest Ru-Ru distance (∼ 3Å), suggesting the long-distance coherent propagation of magnetic excitations driven by the Kitaev couplings. IntroductionQuantum spin liquid is a phase of magnetic insulator in which frustration or quantum fluctuation prohibits magnetic order while keeping spin correlation 1-3 . It induces rich physical phenomena depending on the types of spin liquids, which cannot be realized in standard ordered magnets. Several quantum-spin models have been proposed as possible realizations of quantum spin liquids along with candidate frustrated magnets such as κ- ( Among them, the Kitaev honeycomb model is unique in that the ground state is exactly calculated and known to be a two-dimensional (2D) quantum spin liquid 10 . In this model, spin-1/2 moments, S r , sit on a honeycomb lattice and interact via the bond-dependent Ising couplings; different spin components interact via Ising coupling for the three different bonds of the honeycomb lattice. These anisotropic couplings, called the Kitaev couplings J α S

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“…After the discovery of the spin-pumping effect in ferrimagnetic insulator (yttrium iron garnet, Y 3 Fe 5 O 12 , YIG)/nonmagnetic metal (platinum, Pt) heterosystems by Kajiwara et al [7], there was rapidly emerging interest in the investigation of these structures [6,7,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Since Y 3 Fe 5 O 12 is an insulator with a band gap of 2.85 eV [24] no direct injection of a spin-polarized electron current into the Pt layer is possible.…”

Section: Introductionmentioning

confidence: 99%

Thickness and power dependence of the spin-pumping effect inY3Fe5O12/Pt heterostructures measured by the inverse spin Hall effect

et al. 2015

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The dependence of the spin-pumping effect on the yttrium iron garnet (Y 3 Fe 5 O 12 , YIG) thickness detected by the inverse spin Hall effect (ISHE) has been investigated quantitatively. Due to the spin-pumping effect driven by the magnetization precession in the ferrimagnetic insulator Y 3 Fe 5 O 12 film a spin-polarized electron current is injected into the Pt layer. This spin current is transformed into electrical charge current by means of the ISHE. An increase of the ISHE voltage with increasing film thickness is observed and compared to the theoretically expected behavior. The effective damping parameter of the YIG/Pt samples is found to be enhanced with decreasing Y 3 Fe 5 O 12 film thickness. The investigated samples exhibit a spin mixing conductance of g ↑↓ eff = (3.87 ± 0.21) × 10 18 m −2 and a spin Hall angle between θ ISHE = 0.013 ± 0.001 and 0.045 ± 0.004 depending on the used spin-diffusion length. Furthermore, the influence of nonlinear effects on the generated voltage and on the Gilbert damping parameter at high excitation powers is revealed. It is shown that for small YIG film thicknesses a broadening of the linewidth due to nonlinear effects at high excitation powers is suppressed because of a lack of nonlinear multimagnon scattering channels. We have found that the variation of the spin-pumping efficiency for thick YIG samples exhibiting pronounced nonlinear effects is much smaller than the nonlinear enhancement of the damping.

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One-dimensional spinon spin currents

Cited by 151 publications

References 43 publications

Antiferromagnetic spintronics

Antiferromagnetic spintronics

Magnetic thermal conductivity far above the Néel temperature in the Kitaev-magnet candidate α−RuCl3

Thickness and power dependence of the spin-pumping effect inY3Fe5O12/Pt heterostructures measured by the inverse spin Hall effect

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