High-Pressure Investigation of 2D van der Waals Layered Ferromagnet Cr1.28Te2

Abstract

Cr1+δTe2, a family among two-dimensional (2D) van der Waals (vdW) transition-metal dichalcogenides, has garnered significant interest owing to its tunable structural, electrical, and magnetic properties controlled by the concentration of self-intercalated Cr atoms. Among various external stimuli, pressure provides an additional route to tune the associated physical properties of these materials through modifications of interatomic distances, which can substantially alter the electrical and magnetic properties. In the present study, we report the theoretical and experimental investigation of the pressure-induced structural and electrical properties of Cr1.28Te2 with trigonal (P3̅m1) crystal structure. The pressure-dependent synchrotron X-ray powder diffraction (SXRPD) analysis revealed iso-structural transitions at ∼4.7, ∼9.9, and ∼19.7 GPa, evidenced by the deviation of lattice parameters from linear pressure dependence. The temperature-dependent resistance curves measured over a range of applied pressure show the presence of metal-semiconductor-metal transition near ∼7.8 and ∼16.8 GPa, close to the pressures of the iso-structural transitions. Additionally, a low-temperature resistance minimum observed at low pressures suggests the emergence of localization-related effects. The resistance minimum gradually shifts toward higher temperatures with increasing pressure, indicating the progressive enhancement of localization effect under compression. Further, theoretical calculations suggest that the metallic nature of Cr1.28Te2 below the metal-semiconductor transition (i.e., at low pressure) is dominated by Cr2–3d states, whereas above the transition (at high pressure), the metallicity is governed by Te–3p states. A nonmonotonic evolution of the magnetic state is also observed under pressure, which is likely to originate from modified exchange interactions due to the change in bond lengths under applied pressure. Overall, the combined experimental and theoretical results provide a detailed insight into pressure-induced structural and electrical properties of Cr1.28Te2.