Case News | Nature Materials-Sign-tunable anomalous Hall effect caused by two-dimensional symmetry-protected node structure in ferromagnetic perovskite films

Recently, Professor Changyoung Kim's team from Seoul National University in South Korea published a research work in Nature Materials. In the article, they formally and in writing mentioned the ultraviolet light source products and brand of FERMI INSTRUMENTS. We will continue to work hard on this basis to improve the performance of our products and provide high-quality, high-performance products and technical support to more users around the world.

Article information

Article Introduction

<span magnetism="" and="" spin–orbit="" coupling="" are="" two="" typical="" ingredients="" behind="" topological="" transport="" phenomena="" in="" itinerant="" ferromagnets.="" when="" spin-polarized="" bands="" support="" nodes="" lines="" with="" band="" degeneracy="" that="" can="" be="" lifted="" by="" spin-orbit="" coupling,="" the="" nodal="" structure="" becomes="" source="" of="" berry="" curvature,="" leading="" to="" a="" large="" anomalous="" hall="" effect.="" however,="" two-dimensional="" system="" only="" have="" stable="" there="" is="" appropriate="" crystal="" symmetry.="" <="" span="">
The team of Professor Changyoung Kim of Seoul National University in South Korea and their collaborators published an article in Nature Materials reporting the two-dimensional spin-polarized band structure of perovskite oxides, demonstrating that the symmetry of the two-dimensional spin-polarized bands protects the nodal structure and the points control the sign and magnitude of the anomalous Hall effect. Based on angle-resolved photoelectron spectroscopy (ARPES), transport measurements, and theoretical analysis of SrRuO3 ultrathin films (a representative metallic ferromagnet with spin-orbit coupling), the authors demonstrated the topological band structure of ferromagnetic SRO films, and in particular observed and defined the band structure of ultrathin two-dimensional limit SRO films. Through theoretical analysis, it is also revealed that spin-polarized two-dimensional ferromagnetic bands usually have nodes and NLs that become the source of enhanced Berry curvature. Comparison of band structure measurements using a tight-binding model identified Berry curvature hotspot structures originating from multiple nodes, which led to an unconventional anomalous Hall effect. The thickness, temperature, magnetization, and chemical potential can be controlled by changing the film. This discovery will open up new avenues for studying transport phenomena driven by symmetry-protected nodes in the structure of two-dimensional magnetic systems, and promote the development of magnetic devices based on magnetic topological engineering band structures and new switchable devices based on ferromagnetic ultrathin films.

Article data

Figure 1: Fermi surface (FS) of two-dimensional ferromagnetic perovskite

Figure 2: SrRuO3 thin film angle-resolved photoelectron spectroscopy ARPES data

Figure 3: Non-monotonic anomalous Hall effect (AHE) in SrRuO3 ultra-thin film

Figure 4: Mechanism of sign-tunable anomalous Hall effect (AHE) induced by node lines NLs and nodes in two-dimensional ferromagnetic perovskites

Figure 5: Node structure Berry curvature hotspot and switchable anomalous Hall effect (AHE) of SrRuO3 ultra-thin film

*The article introduction and data are partially quoted from the WeChat public account of "Today's New Materials": (https://mp.weixin.qq.com/s/MmUNGSqUm0TpdfDKZ9IJfQ), with slight modifications.

Related links:

https://www.nature.com/articles/s41563-021-01101-4

http://ares.snu.ac.kr/Equipment.html

https://mp.weixin.qq.com/s/ieHMp_DLDyFQyaxGHmNfRw