Anisotropic Picosecond Spin-Photocurrent from Weyl Semimetal WTe2
March 11, 2020
Publication
- Anisotropic Picosecond Spin-Photocurrent from Weyl Semimetal WTe2
- March 11, 2020
The generation and detection of ultrafast spin current,
preferably reaching a frequency up to terahertz, is the core of
spintronics. Studies have shown that the Weyl semimetal WTe2 is of
great potential in generating spin currents. However, the prior
studies have been limited to the static measurements with the inplane
spin orientation. In this work, we demonstrate a picosecond
spin-photocurrent in a Td-WTe2 thin film via a terahertz time
domain spectroscopy with a circularly polarized laser excitation. The
anisotropic dependence of the circular photogalvanic effect (CPGE)
in the terahertz emission reveals that the picosecond spinphotocurrent
is generated along the rotational asymmetry a-axis.
Notably, the generated spins are aligned along the out-of-plane
direction under the light normally incident to the film surface, which provides an efficient means to manipulate magnetic
devices with perpendicular magnetic anisotropy. A spin-splitting band induced by intrinsic inversion symmetry breaking
enables the manipulation of a spin current by modulating the helicity of the laser excitation. Moreover, CPGE nearly vanishes
at a transition temperature of ∼175 K due to the carrier compensation. Our work provides an insight into the dynamic
behavior of the anisotropic spin-photocurrent of Td-WTe2 in terahertz frequencies and shows a great potential for the future
development of terahertz-spintronic devices with Weyl semimetals.
Researcher/Author: Mengji Chen, Kyusup Lee, Jie Li, Liang Cheng, Qisheng Wang, Kaiming Cai, Elbert E. M. Chia, Haixin Chang, Hyunsoo Yang
ACS Nano 2020, 14, 3539−3545; https://doi.org/10.1021/acsnano.9b09828
Researcher/Author: Mengji Chen, Kyusup Lee, Jie Li, Liang Cheng, Qisheng Wang, Kaiming Cai, Elbert E. M. Chia, Haixin Chang, Hyunsoo Yang
ACS Nano 2020, 14, 3539−3545; https://doi.org/10.1021/acsnano.9b09828