Comparing spin injection in Fe75Co25/Bi2Te3 at GHz and optical excitations
Date
2023-02-13
Journal Title
Journal ISSN
Volume Title
Publisher
Applied Physics Letters
Abstract
Spin-to-charge conversion (S2CC) processes in thin-film heterostructures have attracted much attention in recent years. Here, we describe the S2CC in a 3D topological insulator Bi2Te3 interfaced with an epitaxial film of Fe75Co25. The quantification of spin-to-charge conversion is made with two complementary techniques: ferromagnetic resonance based inverse spin Hall effect (ISHE) at GHz frequencies and femtosecond light-pulse induced emission of terahertz (THz) radiation. The role of spin rectification due to extrinsic effects like anisotropic magnetoresistance (AMR) and planar Hall effects (PHE) is pronounced at the GHz timescale, whereas the THz measurements do not show any detectible signal, which could be attributed to AMR or PHE. This result may be due to (i) homodyne rectification at GHz, which is absent in THz measurements and (ii) laser-induced thermal spin current generation and magnetic dipole radiation in THz measurements, which is completely absent in GHz range. The converted charge current has been analyzed using the spin diffusion model for the ISHE. We note that regardless of the differences in timescales, the spin diffusion length in the two cases is comparable. Our results aid in understanding the role of spin pumping timescales in the generation of ISHE signals.
Description
© 2023 Author(s). This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Vinay Sharma, Rajeev Nepal, Weipeng Wu, E. A. Pogue, Ravinder Kumar, Rajeswari Kolagani, Lars Gundlach, M. Benjamin Jungfleisch, Ramesh C. Budhani; Comparing spin injection in Fe75Co25/Bi2Te3 at GHz and optical excitations. Appl. Phys. Lett. 13 February 2023; 122 (7): 072403. https://doi.org/10.1063/5.0132617 and may be found at https://doi.org/10.1063/5.0132617. This article will be embargoed until 02/13/2024.
Keywords
spin pumping, topological insulator, terahertz radiation
Citation
Vinay Sharma, Rajeev Nepal, Weipeng Wu, E. A. Pogue, Ravinder Kumar, Rajeswari Kolagani, Lars Gundlach, M. Benjamin Jungfleisch, Ramesh C. Budhani; Comparing spin injection in Fe75Co25/Bi2Te3 at GHz and optical excitations. Appl. Phys. Lett. 13 February 2023; 122 (7): 072403. https://doi.org/10.1063/5.0132617