Possible Tricritical Behavior and Anomalous Lattice Softening in van der Waals Itinerant Ferromagnet Fe<sub>3</sub>GeTe<sub>2</sub> under High Pressure
Jiemin Xu, Shuyang Wang, Wenjun Wang, Yonghui Zhou, Xuliang Chen, Zhaorong Yang, Zhe Qu
Abstract
We present a high-pressure study of van der Waals ferromagnetic metal Fe 3 GeTe 2 through electrical transport and Raman scattering measurements in diamond anvil cells at pressures up to 22.4GPa. Upon compression, the ferromagnetic transition temperature T c manifested by a kink in resistance curve decreases monotonically and becomes undiscernable around P c = 10GPa, indicative of suppression of the itinerant ferromagnetism. Meanwhile, by fitting the low temperature resistance to the Fermi liquid behavior of R = R 0 + AT 2 , we found that R 0 shows a cusp-like anomaly and the coefficient A diverges around P c . These transport anomalies imply a tricritical point as commonly observed in itinerant ferromagnets under pressure. Unexpectedly, the Raman-active E 2 g and A 1 g modes soften remarkably after an initial weak hardening and the peak widths of both modes broaden evidently on approaching P c , followed by complete disappearance of both modes above this critical pressure. A possible underlying mechanism for such anomalous lattice softening near P c is discussed.