YRLG Workshop: Correlation and Topology in magnetic materials, July 16th - 18th 2024
Fengrui Yao
Two-dimensional magnetic materials have sparked wide interest in the scientific community due to their potential for a novel atomic-scale platform hosting exotic spin-textures and exhibiting different magnetic phases. Future advances rely on quantitative understanding of their magnetic properties at the nanoscale. By forming tunnel barriers or transistor and measuring their resistance as a function of magnetic field and temperature, the magnetic state of atomically thin semiconducting layered magnetic materials can be probed. Here, I will first introduce our experimental observation of three distinct magnetic phases –one ferromagnetic and two antiferromagnetic– in exfoliated CrBr 3 multilayers. Our results are obtained by magnetoconductance measurements on CrBr 3 tunnel barriers and Raman spectroscopy, in conjunction with density functional theory (DFT) calculations, which enable us to identify the stackings responsible for the different interlayer magnetic couplings. Second, I will introduce our experimental observation of the co-existence of ferro and antiferromagnetic coupling induced by a strain gradient between multilayers of different 2D magnetic materials. Our magnetoconductance measurements show that different thermal dilation coefficient at the interface between multilayers of different 2D magnetic materials can lead to a strain gradient between adjacent layers, resulting in the co-existence of ferro and antiferromagnetic coupling, necessarily accompanied by non-collinear magnetic textures. Third, I show that in CrSP 4 multilayers, besides a high-field spin-flip transition occurring for all thicknesses, the magnetoconductance exhibits an even–odd effect due to a low-field spin-flop transition. Through a quantitative analysis of the phenomena, we determine the interlayer exchange coupling as well as the layer magnetization and show that in CrSP 4 shape anisotropy dominates. Our results reveal the rich behaviour of atomically thin layered antiferromagnets, providing the building blocks of heterostructures for spintronic and magneto-optoelectronic applications.