上海纽约大学

报告摘要：

The discovery of superconductivity in nickelates has drawn great attention. In this talk, I present our first-principles study on infinite-layer nickelates RNiO₂ (R is a rare earth element) and nickelate of Ruddlesden-Popper phase La₃Ni₂O₇. 1) We show that in RNiO₂, there is a substantial hybridization between Ni-d orbitals and conduction bands via an interstitial s orbital [1]. The consequences of this hybridization are i) an intrinsic charge order instability due to the charge transfer from Ni-d orbitals to conduction bands [2] and ii) a change in the Ni-d derived Fermi sheet from electron-like to hole-like along k_z direction [3]. 2) We show that in La₃Ni₂O₇ under high pressure, the most favorable superconducting pairing symmetry is d_xy, if its DFT band structure is exactly reproduced by Wannier fitting [4]. More importantly, we find a strong sensitivity of pairing symmetry to the crystal field splitting between the two Ni e_g orbitals. A slight increase in Ni e_g crystal field splitting changes the pairing symmetry from d_xy to s_± [4]. Our work highlights the multi-orbital nature of nickelate superconductors, which leads to physical properties distinct from cuprate superconductors.

Reference:

[1] Yuhao Gu, Sichen Zhu, Xiaoxuan Wang, Jiangping Hu, Hanghui Chen, “A substantial hybridization between correlated Ni-d orbital and itinerant electrons in infinite-layer nickelates”, Communications Physics 3, 84 (2020).

[2] Hanghui Chen, Yi-feng Yang, Guang-Ming Zhang and Hongquan Liu, “An electronic origin of charge order in infinite-layer nickelates”, Nature Communications 14, 5477 (2023).

[3] Wenjie Sun, Zhicheng Jiang, Chengliang Xia, Bo Hao, Yueying Li, Shengjun Yan, Maosen Wang, Hongquan Liu, Jianyang Ding, Jiayu Liu, Zhengtai Liu, Jishan Liu, Hanghui Chen, Dawei Shen, Yuefeng Nie, “Electronic Structure of Superconducting Infinite-Layer Lanthanum Nickelates”, arXiv:2403.07344 (2024).

[4] Hongquan Liu, Chengliang Xia, Shengjie Zhou, Hanghui Chen, “Role of crystal-field-splitting and longerange-hoppings on superconducting pairing symmetry of La₃Ni₂O₇”, arXiv:2311.07316 (2023).

报告人简介：

Dr. Hanghui Chen is an associate professor of physics at NYU Shanghai and a global network associate professor of physics at New York University. He obtained his bachelor’s degree in Physics from Peking University and his Ph.D. degree in Physics from Yale University. Before joining NYU Shanghai’s faculty, Dr. Chen held a postdoc position in the Department of Physics at Columbia University. Dr. Chen's research area is at the intersection of condensed matter physics and materials science. He uses state-of-the-art first-principles calculations to study electronic, magnetic, structural, and superconducting properties of quantum materials, with a particular emphasis on complex oxides and oxide heterostructures.

会议室：M楼249会议室

邀请人：张坚地（9454）