TY - JOUR A1 - Xu, Han-Xiang A1 - Shimizu, Makoto A1 - Guterding, Daniel A1 - Otsuki, Junya A1 - Jeschke, Harald O. T1 - Pressure evolution of electronic structure and magnetism in the layered van der Waals ferromagnet CrGeTe3 JF - Physical Review B N2 - Layered van der Waals ferromagnets, which preserve their magnetic properties down to exfoliated monolayers, are fueling an abundance of fundamental research and nanoscale device demonstration. CrGeTe3 is a prime example of this class of materials. Its temperature-pressure phase diagram features an insulator-to-metal transition and a significant increase in ferromagnetic Curie-Weiss temperatures upon entering the metallic state. We use density functional theory to understand the magnetic exchange interactions in CrGeTe3 at ambient and elevated pressures. We calculate Heisenberg exchange couplings, which provide the correct ferromagnetic ground state and explain the experimentally observed pressure dependence of magnetism in CrGeTe3. Furthermore, we combine density functional theory with dynamical mean-field theory to investigate the effects of electronic correlations and the nature of the high-pressure metallic state in CrGeTe3. Y1 - 2023 U6 - https://doi.org/https://doi.org/10.1103/PhysRevB.108.125142 IS - Vol. 108 PB - American Physical Society ER - TY - JOUR A1 - Ebad-Allah, Jihaan A1 - Guterding, Daniel A1 - Varma, Meera A1 - Diware, Mangesh A1 - Ganorkar, Shraddha A1 - Jeschke, Harald A1 - Kuntscher, Christine T1 - Near room-temperature ferromagnetism from double exchange in the van der Waals material CrGeTe3: Evidence from optical conductivity under pressure JF - Physical Review B N2 - The unexpected discovery of intrinsic ferromagnetism in layered van der Waals materials has sparked interest in both their fundamental properties and their potential for novel applications. Recent studies suggest near roomtemperature ferromagnetism in the pressurized van der Waals crystal CrGeTe3. We perform a comprehensive experimental and theoretical investigation of magnetism and electronic correlations in CrGeTe3, combining broad-frequency reflectivity measurements with density functional theory and dynamical mean-field theory calculations. Our experimental optical conductivity spectra trace the signatures of developing ferromagnetic order and of the insulator-to-metal transition (IMT) as a function of temperature and hydrostatic pressure. With increasing pressure, we observe the emergence of a midinfrared feature in the optical conductivity, indicating the development of strong orbital-selective correlations in the high-pressure ferromagnetic phase. We find a distinct relationship between the plasma frequency and Curie temperature of CrGeTe3, which strongly suggests that a double-exchange mechanism is responsible for the observed near room-temperature ferromagnetism. Our results clearly demonstrate the existence of a charge-transfer gap in the metallic phase, ruling out its previously conjectured collapse under pressure. Y1 - 2025 U6 - https://doi.org/10.1103/PhysRevB.111.L140402 VL - 111 PB - American Physical Society ER - TY - JOUR A1 - Scharf, Gili A1 - Guterding, Daniel A1 - Hen, Bar A1 - Sarte, Paul M. A1 - Ortiz, Brenden R. A1 - Rozenberg, Gregory Kh. A1 - Holder, Tobias A1 - Wilson, Stephen D. A1 - Jeschke, Harald O. A1 - Ron, Alon T1 - Pressure tuning of intrinsic and extrinsic sources to the anomalous Hall effect in CrGeTe3 JF - Physical Review Research N2 - The integrated Berry curvature is a geometric property that has dramatic implications for material properties. This study investigates the integrated Berry curvature and other contributions to the anomalous Hall effect in CrGeTe3 as a function of pressure. The anomalous Hall effect is absent in the insulating phase of CrGeTe3 and evolves with pressure in a domelike fashion as pressure is applied. The dome's edges are characterized by Fermi surface deformations, manifested as mixed electron and hole transport. We corroborate the presence of bipolar transport using ab initio calculations, which also predict a nonmonotonic behavior of the Berry curvature as a function of pressure. Quantitative discrepancies between our calculations and experimental results indicate that additional scattering mechanisms, which are also strongly tuned by pressure, contribute to the anomalous Hall effect in CrGeTe3. Y1 - 2025 U6 - https://doi.org/10.1103/PhysRevResearch.7.013127 VL - 7 IS - 1 SP - 1 EP - 8 PB - American Physical Society ER -