Probing and controlling magnetic states in 2D layered magnetic materials

The discovery of atomic monolayer magnetic materials has triggered significant interest in the magnetism/spintronics and 2D van der Waals materials communities. Here we review recent progress in this rapidly growing field. We survey the physical properties of the large class of layered magnetic materials, and discuss recent advances in the study of these materials in the 2D limit. We then overview the optical and electrical techniques used for probing 2D magnetic materials (for reading their magnetic states) and the mechanisms for reorienting and/or switching 2D magnets by electric fields (for writing). Emerging device concepts based on magnetic van der Waals heterostructures are also discussed. We conclude with the future challenges and opportunities in this area of research. The emergence of 2D magnetic materials presents a unique opportunity to study magnetism and spintronics devices in new regimes. This Review surveys the basic properties of these materials, methods to read and write their magnetic states, and emerging device concepts. Key pointsThere is a large class of layered magnetic materials with unique magnetic properties, which provides an ideal platform to study magnetism and spintronics device concepts in the 2D limit.Magneto-optical and electrical probes are powerful techniques for probing or reading the magnetic states of these materials.Because these materials are atomically thin, their magnetic states can be effectively controlled or switched by external perturbations other than magnetic fields, such as electric fields, free carrier doping and strain.New materials concepts, such as magnetizing 2D semiconductors by magnetic proximity coupling, and new devices, such as spin tunnel field-effect transistors, are rapidly emerging.Although rapid progress has already been made, there are many opportunities and challenges remaining in this young field.