Spin Hall conductivity in topological Dirac semimetals

Taguchi, Katsuhsia; Oshima, Daisuke; Yamaguchi, Yusuke; Hashimoto, Takahiro; Tanaka, Yukio; Sato, Masatoshi

doi:10.1103/physrevb.101.235201

Cited by 16 publications

(9 citation statements)

References 22 publications

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“…In the present work, we theoretically propose a longrange transmission of spin mediated by the surface electronic states of topological Dirac semimetals (TDSMs). TDSM is a class of three-dimensional (3D) crystalline materials having pair(s) of Dirac nodes in the electronic band structure in the bulk [33][34][35]. The TDSM phase is experimentally realized in Na 3 Bi [36,37] and Cd 3 As 2 [38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Long-range spin transport on the surface of topological Dirac semimetal

Araki,

Misawa,

Nomura

2021

Preprint

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We theoretically propose the long-range spin transport mediated by the gapless surface states of topological Dirac semimetal (TDSM). Low-dissipation spin current is a building block of nextgeneration spintronics devices. While conduction electrons in metals and spin waves in ferromagnetic insulators (FMIs) are the major carriers of spin current, their propagation length is inevitably limited due to the Joule heating or the Gilbert damping. In order to suppress dissipation and realize longrange spin transport, we here make use of the spin-helical surface states of TDSMs, such as Cd3As2 and Na3Bi, which are robust against disorder. Based on a junction of two FMIs connected by a TDSM, we demonstrate that the magnetization dynamics in one FMI induces a spin current on the TDSM surface flowing to the other FMI. By both the analytical transport theory on the surface and the numerical simulation of real-time evolution in the bulk, we find that the induced spin current takes a universal semi-quantized value that is insensitive to the microscopic coupling structure between the FMI and the TDSM. We show that this surface spin current is robust against disorder over a long range, which indicates that the TDSM surface serves as a promising system for realizing spintronics devices.

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Section: Introductionmentioning

confidence: 99%

Long-range spin transport on the surface of topological Dirac semimetal

Araki,

Misawa,

Nomura

2021

Preprint

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“…For both effects, the conversion efficiency is commonly characterized by the spin Hall angle: the ratio of the induced transverse spin (charge) current to the applied charge (spin) current. Following intensive efforts on quantifying the spin Hall angle of transition metals and their alloys 7 , studies have also been extended to explore other materials systems [10][11][12][13][14][15] for more tunable spin-charge conversion, which is potentially useful when it comes to endowing spintronic devices with new functionalities.…”

Section: Introductionmentioning

confidence: 99%

“…First of all, when an electric field E is applied without a magnetic field, a spin Hall current, which takes the form Q z = σ 0 SH E × ẑ, 15,26 is generated. One notable difference from the spin Hall effect in non-topological materials such as heavy metals is that in a TDSM, only the spin current with spin polarized in the z-direction is generated, irrespective of the electric field direction.…”

Section: Introductionmentioning

confidence: 99%

Tunable spin-charge conversion in class-I topological Dirac semimetals

Li,

Shen,

Zhang

2021

Preprint

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We theoretically demonstrate that type-I topological Dirac semimetals (TDSMs) can provide a platform for realizing both electrically and magnetically tunable spin-charge conversion. With time-reversal symmetry, the spin component along the uniaxial rotation axis (z-axis) is approximately conserved, which leads to an anisotropic spin Hall effect-the resulting spin Hall current relies on the relative orientation between the external electric field and the z-axis. The application of a magnetic field, on the other hand, breaks timereversal symmetry, driving the TDSM into a Weyl semimetal phase and, consequently, partially converting the spin current to a charge Hall current. Using the Kubo formulas, we numerically evaluate the spin and charge Hall conductivities based on a low-energy TDSM Hamiltonian together with the Zeeman coupling. Besides the conventional tensor element of the spin Hall conductivity σ z xy , we find that unconventional components, such as σ x xy and σ y xy , also exist and vary as the magnetic field is rotated. Likewise, the charge Hall conductivity also exhibits appreciable tunability upon variation of the magnetic field.We show that such tunability originates from the interplay of symmetry and band topology of the TDSMs.

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“…Regarding the aforementioned background, we here aim to understand the characteristics of such a magnetic nodal-line state by introducing magnetization in nonmagnetic topological semimetals, in particular the model of topological Dirac semimetal (TDSM) as the starting point. TDSM is characterized by a pair of spin-degenerate Dirac points protected by rotational symmetries of crystal, [51][52][53] and is realized in Na 3 Bi, 17,54) Cd 3 As 2 , 18,[55][56][57][58] etc. The Dirac points in TDSM are realized by the band inversion from spin-orbit coupling, and are protected by crystalline symmetries.…”

Section: Introductionmentioning

confidence: 99%

Nodal lines and boundary modes in topological Dirac semimetals with magnetism

Araki,

Watanabe,

Nomura

2021

Preprint

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Nodal-line semimetals with magnetic orders have been theoretically predicted and experimentally observed in only few compounds. We theoretically explore the electronic structure in bulk and boundary of such a magnetic nodalline state by introducing magnetism in topological Dirac semimetal (TDSM). TDSMs, such as Cd 3 As 2 and Na 3 Bi, are characterized by a pair of spin-degenerate Dirac points protected by rotational symmetries of crystals. By introducing local magnetic moments coupled to the electron spins in the lattice model of TDSM, we show that the TDSM can turn into either a Weyl semimetal or a nodal-line semimetal, which is determined by the orbital dependence in the exchange coupling and the direction of magnetization formed by the magnetic moments. In this magnetic nodal-line semimetal state, we find zero modes with drumhead-like band structure at the boundary that are characterized by the topological number of Z. Those zero modes are numerically demonstrated by introducing magnetic domain walls in the lattice model.

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Spin Hall conductivity in topological Dirac semimetals

Cited by 16 publications

References 22 publications

Long-range spin transport on the surface of topological Dirac semimetal

Long-range spin transport on the surface of topological Dirac semimetal

Tunable spin-charge conversion in class-I topological Dirac semimetals

Nodal lines and boundary modes in topological Dirac semimetals with magnetism

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