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Proceedings Paper

New variants of the Edelstein effect (Conference Presentation)
Author(s): Masato Hamada; Taiki Yoda; Emi Minamitani; Motoaki Hirayama; Takehito Yokoyama; Shuichi Murakami
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Paper Abstract

In the Edelstein effect, a current in the crystal induces a spin polarization. It occurs in crystals without inversion symmetry, as studied in Rashba systems and in the surface of topological insulators. The spin polarization vanishes in equilibrium, but in the presence of the current, the off-equilibrium electron distribution leads to nonzero spin polarization, due to the spin-split band structure. We propose an analogous effect for orbital angular momentum. For example, in a crystal with helical structure such as tellurium (Te), we propose that a current along the helical axis induces an orbital magnetization. This is analogous to solenoids in classical electrodynamics. Within this analogy to solenoids, we quantify this effect by introducing a dimensionless parameter, which represents a number of turns in the unit cell when regarded as a classical solenoid. We show that it can become much larger than unity, i.e. it is much larger than the value naïvely expected from the lattice structure. Moreover, we propose a similar effect appears for phonons. In crystals, each phonon eigenmode has angular momentum due to rotational motions of the nuclei, but their sum is zero in equilibrium. Meanwhile a heat current in the Te crystal induces a nonzero total angular momentum. We evaluate this effect for GaN and Te by ab initio calculation, and propose experiments to measure this effect.

Paper Details

Date Published: 18 September 2018
Proc. SPIE 10732, Spintronics XI, 107322I (18 September 2018); doi: 10.1117/12.2323431
Show Author Affiliations
Masato Hamada, Tokyo Institute of Technology (Japan)
Taiki Yoda, Tokyo Institute of Technology (Japan)
Emi Minamitani, The Univ. of Tokyo (Japan)
Motoaki Hirayama, RIKEN (Japan)
Takehito Yokoyama, Tokyo Institute of Technology (Japan)
Shuichi Murakami, Tokyo Institute of Technology (Japan)

Published in SPIE Proceedings Vol. 10732:
Spintronics XI
Henri-Jean Drouhin; Jean-Eric Wegrowe; Manijeh Razeghi; Henri Jaffrès, Editor(s)

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