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TT: Fachverband Tiefe Temperaturen
TT 37: Correlated Electrons: Poster
TT 37.41: Poster
Mittwoch, 19. März 2025, 15:00–18:00, P4
Role of interlayer coupling and anisotropy in 1T-TaS2 studied by ellipsometry — •Achyut Tiwari1, Renjith M. Roy1, Christian Prange1, Yuan Yan2, Bruno Gompf1, and Martin Dressel1 — 11. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany — 2School of Physics, Nankai University, Tianjin, 300071 China
The layered transition metal dichalcogenide 1T-TaS2 has attracted considerable attention due to its rich electronic phase diagram, characterized by multiple charge density wave (CDW) phases. With decreasing temperature, the material transitions from a metallic incommensurate phase to a metallic nearly commensurate phase and finally to an insulating commensurate phase featuring the star-of-David lattice distortion. The metal-insulator transition (MIT) is a first-order phase transition that exhibits hysteresis during cooling and heating, with an additional intermediate phase in the 215 K-280 K range upon heating. Here, temperature-dependent ellipsometry revealed pronounced anisotropy between in-plane and out-of-plane responses, attributable to significant interlayer interactions. The temperature-dependent out-of-plane dielectric constant exhibited marked changes across the MIT, highlighting the role of interlayer coupling. Furthermore, the effective medium approximation confirmed the existence of the intermediate phase during heating, providing a microscopic description. These findings underscore the importance of interlayer coupling in layered materials and elucidate on the previously unexplored intermediate phase of 1T-TaS2.
Keywords: Charge density wave; Metal-insulator transition; Ellipsometry; Effective medium approximation; Anisotropy