Topological Skyrmion-Based Spin-Torque-Diode Effect in Magnetic Tunnel Junctions

The Internet of Things market's rapid growth is increasing the need for energy-efficient nanoscale hardware for edge computing and microwave applications. Magnetic tunnel junctions (MTJs), as key components of spintronic microwave technology, offer a promising pathway for compact and high-performance microwave detectors. Simultaneously, the emerging field of skyrmionics combines concepts from topology and spintronics, opening new avenues for device innovation. This study demonstrates the electrical excitation and detection of skyrmion dynamics using a topological spin-torque diode (STD) with a nanoscale MTJ on a skyrmionic material at room temperature and for a wide region of applied fields, including the zero-field case. Quantitative Magnetic Force Microscopy measurements confirm the presence of a single skyrmion in the MTJ-free layer. Electrical measurements reveal the electrical excitation via spin-transfer torque (STT) of a skyrmion resonant mode with frequencies near 4 GHz and a selectivity one order of magnitude smaller than the uniform modes excited in the same device. Micromagnetic simulations identify these dynamics to the breathing mode and highlight the impact of thickness-dependent magnetic parameters (magnetic anisotropy field and Dzyaloshinkii-Moriya interaction) in both stabilizing and exciting the magnetic skyrmions. This work marks a milestone in the development of topological spin microwave devices.