Spin transport and spin conversion in compound semiconductor with non-negligible spin-orbit interaction

Yamamoto, Akiyori; Ando, Yoshinori; Shinjo, Teruya; Uemura, Tetsuya; Shiraishi, Masashi

doi:10.1103/physrevb.91.024417

Cited by 22 publications

(23 citation statements)

References 37 publications

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“…"#$ . We used a well-established spin diffusion model including the contribution of sample geometry for the estimation [38][39][40] . For the Pt (Ta) electrode sample, the injected spin current density !…”

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Strong evidence for d-electron spin transport at room temperature at a LaAlO3/SrTiO3 interface

et al. 2017

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3A two-dimensional electron gas (2DEG) generated between LaAlO 3 (LAO) and SrTiO 3 (STO) consists of itinerant d-orbital electrons in the t 2g orbitals of Ti in STO 1,2 . This anisotropic orbit induces ferromagnetism, superconductivity, and even their coexistence at LAO/STO interfaces [3][4][5][6][7][8] . The subbands of LAO/STO interfaces have a complicated structure and cross each other due to the strong orbital hybridization 9-12 , resulting in the enhancement of spin-orbit coupling and nonmonotonic gate tunability [13][14][15][16] . It is believed that long-rage spin transport in the 2DEGs at LAO/STO interfaces is difficult to achieve due to the Rashba were prepared by using a high-power sputtering process, resulting in the pseudo-Ohmic contact at the Py-LAO/STO interface. The pseudo-Ohmic contact allows injecting spins from the Py and also detecting spin transport signals in the detector electrode. We applied a microwave (f = 9.63 GHz) and a static magnetic field with angle ! ! to the +x-axis (see Fig. 1a) to the Py strip on the LAO layer in order to excite the ferromagnetic resonance (FMR) of the Py. Under condition of the FMR, spin angular momentum is transferred from the Py to the 2DEG, resulting in the generation of pure spin current in the 2DEG 26,27 . The pure spin current in the 2DEG was detected by using the independent, separate NM (=Pt or Ta) strip deposited on the LAO layer. The propagating pure spin current is absorbed in the NM and converted to a charge current by the inverse spin Hall effect (ISHE) of the NM 28 , generating an electromotive force Information for details); the symmetric component is described in Fig. 2d.The ISHE has a characteristic symmetry in a relationship between the pure spin current direction ! ! , the charge current direction ! ! and the spin polarization vector !, i.e.where ! !"# is the spin Hall angle, ! is the electronic charge and ℏ is the Dirac constant 28 .The symmetry in equation (1) indicates that the polarity of the EMF is reversed when the direction of the external magnetic field, i.e., the direction of the spin polarization vector of the pure spin current is reversed. Figs. 2a-c and 2d-e show the FMR spectrum and EMF at ! ! = 0°, 90° and 180°, respectively. The ! ! dependence of the EMFs is consistent with the symmetry of the ISHE shown in equation (1): the polarities of electromotive forces at ! ! = 0° and 180°were reversed, and the signal at ! ! = 90° disappeared. These results strongly suggest that the observed EMFs under the FMR conditions can be ascribed to the ISHE in the Pt, i.e., the propagation of pure spin current in the 2DEG at RT. Deconvolutions of the EMFs were performed for ! ! = 0° and 180° and we used ( Table I. Notably, the sign of ! !"#$ obtained using a Ta electrode was opposite to that of Pt, which strongly supports the notion that long-range spin transport in the 2DEG indeed has been successfully achieved. It is important to note that the Py and Pt or Ta strips are only connected via the 2DEG at the LAO/STO interface, since the STO and t...

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Strong evidence for d-electron spin transport at room temperature at a LaAlO3/SrTiO3 interface

et al. 2017

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“…In this study, the τ in the pentacene films is estimated as follows: because a diffusive transport of the spin current in the pentacene films has been assumed, 9 we can use a relationship [14][15][16][17][18][19] which is expressed as,…”

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Spin current relaxation time in thermally evaporated pentacene films

et al. 2017

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The spin current relaxation time (τ) in thermally evaporated pentacene films was evaluated with the spin-pump-induced spin transport properties and the charge current transport properties in pentacene films. Under an assumption of a diffusive transport of the spin current in pentacene films, the zero-field mobility and the diffusion constant of holes in pentacene films were experimentally obtained to be ~8.0× 10 -7 m 2 /Vs and ~2.0× 10 -8 m 2 /s, respectively. Using those values and the previously obtained spin diffusion length in pentacene films of 42±10 nm, the τ in pentacene films was estimated to be 150±120 ns at room temperature. This estimated τ in pentacene films is long enough for practical use as a spintronic material.

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“…15,16 In this case, the conductance mismatch problem related to spin injection with spin-pumping is negligible. [17][18][19] Our sample structure and experimental set up is illustrated in Figure 1. Spin transport in pentacene is observed as follows: in palladium(Pd)/evaporated-pentacene/Ni 80 Fe 20 tri-layer samples, a spin-pump-induced pure spin current, J S , driven by ferromagnetic resonance (FMR) 15,16 of the Ni 80 Fe 20 film is generated in the pentacene layer.…”

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Spin-pump-induced spin transport in a thermally evaporated pentacene film

Tani

Teki

Shikoh

2015

Applied Physics Letters

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We report the spin-pump-induced spin transport properties of a pentacene film prepared by thermal evaporation. In a palladium(Pd)/pentacene/Ni 80 Fe 20 tri-layer sample, a pure spin-current is generated in the pentacene layer by the spin-pumping of Ni 80 Fe 20 , which is independent of the conductance mismatch problem in spin injection. The spin current is absorbed into the Pd layer, converted into a charge current with the inverse spin-Hall effect in Pd, and detected as an electromotive force. This is clear evidence for the pure spin current at room temperature in pentacene films prepared by thermal evaporation.

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Spin transport and spin conversion in compound semiconductor with non-negligible spin-orbit interaction

Cited by 22 publications

References 37 publications

Strong evidence for d-electron spin transport at room temperature at a LaAlO3/SrTiO3 interface

Strong evidence for d-electron spin transport at room temperature at a LaAlO3/SrTiO3 interface

Spin current relaxation time in thermally evaporated pentacene films

Spin-pump-induced spin transport in a thermally evaporated pentacene film

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