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MM: Fachverband Metall- und Materialphysik
MM 6: Phase Transformations
MM 6.9: Vortrag
Montag, 17. März 2025, 18:00–18:15, H10
Tuning excitonic transition by Cr doping and associated lattice softening in the vdW chalcogenide: Ta2NiSe5 — •Isha Isha1, Koushik Chakraborty1, Aditi Agrawal1, M. Isobe2, and Arvind Kumar Yogi1 — 1UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001, India — 2Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany
We have successfully grown defect free ultra-high quality single crystals of Cr doped Ta2NiSe5, maximum of 10% at Ni site in the lattice. Our preliminary STM results unambiguous provide clear signature of CDW phase, vdW layers and the vdW gap for Ta2NiSe5 which was found to be ~3.5 Å. We found a clear anomaly at the critical temperature Tc = 326 K in our transport measurement over rod shaped crystals - a transition into an excitonic insulator ground state as reported for parent Ta2NiSe5 compound. It is noteworthy to highlight our finding that Cr doping significantly suppresses the insulating ground state and the 10% doping reduces the resistivity of three orders. In addition, our detailed high-temperature Raman scattering for parent as well as Cr doping reveals sharp Raman modes and significant shift and suppression for 230 cm-1 phonon mode which might be associated with electron-phonon coupling, which may helps in resistivity drop as evident in our transport data. In addition, our detailed Raman scattering study suggests the persistence of lattice softening which may be due to strong electron-lattice coupling, and the origin is presumably due to strong excitonic fluctuations.
Keywords: Structural phase transition; Quantum Materials; X-ray diffraction; Raman Scattering; Symmetry-breaking