Nearly Room-Temperature Ferromagnetism in a Pressure-Induced Correlated Metallic State of the van der Waals Insulator <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>CrGeTe</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>
Dilip Bhoi, Jun Gouchi, Naoka Hiraoka, Yufeng Zhang, Norio Ogita, Takumi Hasegawa, Kentaro Kitagawa, Hidenori Takagi, Kee Hoon Kim, Yoshiya Uwatoko
Abstract
A complex interplay of different energy scales involving Coulomb repulsion, spin-orbit coupling, and Hund's coupling energy in 2D van der Waals (vdW) material produces a novel emerging physical state. For instance, ferromagnetism in vdW charge transfer insulator ${\mathrm{CrGeTe}}_{3}$ provides a promising platform to simultaneously manipulate the magnetic and electrical properties for potential device implementation using few nanometers thick materials. Here, we show a continuous tuning of magnetic and electrical properties of a ${\mathrm{CrGeTe}}_{3}$ single crystal using pressure. With application of pressure, ${\mathrm{CrGeTe}}_{3}$ transforms from a ferromagnetic insulator with Curie temperature ${T}_{C}\ensuremath{\sim}66\text{ }\text{ }\mathrm{K}$ at ambient condition to a correlated 2D Fermi metal with ${T}_{C}$ exceeding $\ensuremath{\sim}250\text{ }\text{ }\mathrm{K}$. Notably, absence of an accompanying structural distortion across the insulator-metal transition (IMT) suggests that the pressure induced modification of electronic ground states is driven by electronic correlation furnishing a rare example of bandwidth-controlled IMT in a vdW material.