腾讯会议：215-323-824

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报告摘要：

High pressure x-ray diffraction up to 30 GPa and resonant inelastic x-ray scattering spectroscopy up to 52 GPa were used to study how the structural and electronic properties of UTe₂ evolve with pressure at room temperature. High pressure x-ray diffraction studies in UTe₂ up to 30 GPa at room temperature revealed an orthorhombic to tetragonal phase transition between 5 and 7 GPa [1,2,3], with a large volume collapse of nearly 10% and a nearest U-U distance increase by about 4% [1]. In conjunction, resonant x-ray emission spectroscopy and partial fluorescence yield x-ray absorption spectra clearly demonstrate a U intermediate valence of nearly +3.74 at 1.8 GPa and room temperature. With increasing pressure, the U valence shifts towards 4+, passes through a peak at 2.8 GPa, and then decreases towards 3+ and settles to nearly a constant value above 15 GPa and up to 52 GPa [1]. This lower to higher symmetry transition suggests less 5f electron participation in bonding when the weakly correlated superconducting phase in the tetragonal structure of UTe₂ appears.

[1] Structural transition and uranium valence change in UTe₂ at high pressure revealed by x-ray diffraction and spectroscopy. Physics Review B, 110, 075140 (2024)

[2] Pressure-induced structural transition and new superconducting phase in UTe₂, J. Phys. Soc. Jpn. 92, 044702 (2023).

[3] Metastable phase of UTe₂ formed under high pressure above 5 GPa, Phys. Rev. Mat. 6, 114801 (2022).

报告人简介：

Dr. Eric Lee-Wong got his bachelors degree at the University of Washington in Seattle and his PhD at the University of California San Diego (UCSD) in 2024. He is currently a post-doctoral researcher at the Brian Maple Laboratory at UCSD researching correlated heavy fermion materials under extreme conditions of high pressure. He did his graduate research focusing on nitrogen vacancy optically detected magnetic resonance spectroscopy on 2D materials and resonant in-elastic x-ray spectroscopy studies on UTe₂ and UFe₂Si₂ under high pressure in diamond anvil cells. Today he will be talking about the later research he did with Brian Maple, studying the novel superconducting heavy fermion material UTe₂.

邀请人：程金光 研究员

　　　　王铂森 研究员

联系人：王慧颖 why@iphy.ac.cn