Work

Mott gap softening coinciding with spin correlations collapse in α- RuCl 3

Year: 2025

Type: article

Abstract: The Mott insulator α − RuC l 3 , featuring the intertwined interplay of spin-orbit coupling and Kitaev spin correlations, provides an unparalleled platform for probing quantum many-body physics. Using scanning tunneling microscopy/spectroscopy, we compare temperature-dependent dI / dV spectra between grown monolayers and exfoliated bulk samples. Both systems exhibit pronounced Mott gap softening near 110 K, manifested by spectral weight transfer from Hubbard bands toward the Fermi level, resulting in low-energy correlated charge delocalization. Although this gap softening coincides with Kitaev paramagnetic and structural phase transitions in bulk crystals, monolayer studies provide compelling insights. By eliminating structural phase transition in monolayer sample, we suggest that spin correlations, rather than Coulomb interactions alone, may govern charge dynamics within the Mott-Hubbard framework, challenging conventional Mott-Hubbard paradigms. These results resolve a long-standing controversy regarding the Mott gap magnitude in α − RuC l 3 and experimentally confirm the critical role of spin correlations in Mott physics.

Source: Physical Review Research

DOI: 10.1103/nbfx-x8f6

Authors: Wei Yue, Xiaohu Zheng, Chongli Yang, Kun Peng, Rui-Rui Du

Institutions: Peking University, Shanghai Institute of Microsystem and Information Technology, Beijing Academy of Quantum Information Sciences, University of Chinese Academy of Sciences

Language: English

Topic: Advanced Condensed Matter Physics

Subfield: Condensed Matter Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,625

Funders: Chinese Academy of Sciences, National Key Research and Development Program of China, Open Research Fund of State Key Laboratory of Bioelectronics