Nano CrGeTe₃: Topological Hall Effect in the Metallic State under High Pressure

The ferromagnetic (FM) properties of the van der Waals charge transfer insulator CrGeTe₃ provide a promising avenue for concurrently controlling magnetic and electrical characteristics. This enables the potential integration of devices using nanoscale materials. In this research, we have effectively produced highly stable CrGeTe₃ nanosheets by utilizing a Cr₂Te₃ template. Additionally, we show that the magnetic and electrical characteristics of CrGeTe₃ single crystals can be continuously adjusted through the application of pressure. Electrical transport measurements reveal that CrGeTe₃ transitions from an insulator under ambient conditions to a metallic state at 6.02 GPa. After reaching 25.33 GPa, CrGeTe₃ undergoes a phase transition from the FM state to the Néel antiferromagnetic state at 30 K. This transition highlights the important impact of pressure on exchange interactions, corroborating density functional theory calculations. Micromagnetic simulation shows that the high-pressure topological Hall effect above 25.33 GPa originates from the Néel-type skyrmion. The interaction observed between magnetic couplings and high pressure provides crucial insights into the novel topological transport phenomena and their underlying physics, which is valuable for advancing spintronics devices and other emerging electronic technologies.