Open AccessTopological Surface‐Dominated Spintronic THz Emission in Topologically Nontrivial Bi 1− x Sb x Films
Author(s) -
Park Hanbum,
Rho Seungwon,
Kim Jonghoon,
Kim Hyeongmun,
Kim Dajung,
Kang Chul,
Cho MannHo
Publication year - 2022
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202200948
Subject(s) - spintronics , materials science , condensed matter physics , physics , surface (topology) , topology (electrical circuits) , ferromagnetism , mathematics , combinatorics , geometry
Topological materials have significant potential for spintronic applications owing to their superior spin–charge interconversion. Here, the spin‐to‐charge conversion (SCC) characteristics of epitaxial Bi 1− x Sb x films is investigated across the topological phase transition by spintronic terahertz (THz) spectroscopy. An unexpected, intense spintronic THz emission is observed in the topologically nontrivial semimetal Bi 1− x Sb x films, significantly greater than that of Pt and Bi 2 Se 3 , which indicates the potential of Bi 1− x Sb x for spintronic applications. More importantly, the topological surface state (TSS) is observed to significantly contribute to SCC, despite the coexistence of the bulk state, which is possible via a unique ultrafast SCC process, considering the decay process of the spin‐polarized hot electrons. This means that topological material‐based spintronic devices should be fabricated in a manner that fully utilizes the TSS, not the bulk state, to maximize their performance. The results not only provide a clue for identifying the source of the giant spin Hall angle of Bi 1− x Sb x , but also expand the application potential of topological materials by indicating that the optically induced spin current provides a unique method for focused‐spin injection into the TSS.