Recent progress of the skyrmionic magnetic tunnel junctions

Magnetic skyrmions are nonlinear spin textures characterized by unique topological stability and dynamic properties. Due to their nanometric size, stable spin structure, and susceptible to different manipulation methods, skyrmions are regarded as promising information carriers for next-generation spintronic memory and computing devices. Three prerequisites should be achieved prior to device applications: generation, manipulation, and detection. In recent years, significant progress have been made in the generation and manipulation of skyrmions; however, there have been relatively few reports on efficient electrical detection of skyrmions, which hinders their application. Based on the quantum-mechanical effect and the spin-dependent density of states, the tunneling magnetoresistance (TMR) enables the conversion of the presence and absence of skyrmion into robust electrical signals with large on/off ratios, providing a viable approach for the efficient electrical detection of skyrmions. This review highlights three characteristic TMR effects associated with skyrmions: conventional tunnel magnetoresistance (TMR), tunnel anisotropic magnetoresistance (TAMR), and non-collinear magnetoresistance (NCMR). We further present an overview of the classification and development of magnetic tunnel junctions (MTJs), along with the latest advances in skyrmionic MTJs. In the end, the application prospects of skyrmionic MTJs and projections of their future developments will be discussed.