Sign-tunable anomalous Hall effect induced by two-dimensional symmetry-protected nodal structures in ferromagnetic perovskite thin films

Byungmin Sohn, Eunwoo Lee, Se Young Park, Wonshik Kyung, Jinwoong Hwang, Jonathan D. Denlinger, Minsoo Kim, Donghan Kim, Bongju Kim, Hanyoung Ryu, Soonsang Huh, Ji Seop Oh, Jong Keun Jung, Dongjin Oh, Younsik Kim, Moonsup Han, Tae Won Noh, Bohm Jung Yang, Changyoung Kim

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

Magnetism and spin–orbit coupling are two quintessential ingredients underlying topological transport phenomena in itinerant ferromagnets. When spin-polarized bands support nodal points/lines with band degeneracy that can be lifted by spin–orbit coupling, the nodal structures become a source of Berry curvature, leading to a large anomalous Hall effect. However, two-dimensional systems can possess stable nodal structures only when proper crystalline symmetry exists. Here we show that two-dimensional spin-polarized band structures of perovskite oxides generally support symmetry-protected nodal lines and points that govern both the sign and the magnitude of the anomalous Hall effect. To demonstrate this, we performed angle-resolved photoemission studies of ultrathin films of SrRuO3, a representative metallic ferromagnet with spin–orbit coupling. We show that the sign-changing anomalous Hall effect upon variation in the film thickness, magnetization and chemical potential can be well explained by theoretical models. Our work may facilitate new switchable devices based on ferromagnetic ultrathin films.

Original languageEnglish
Pages (from-to)1643-1649
Number of pages7
JournalNature Materials
Volume20
Issue number12
DOIs
StatePublished - Dec 2021

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