On the edge of Mott(ness): Li0.9Mo6O17 , a curious quasi-1D material that sometimes superconducts
Prof. Piotr Chudziński, Institute of Fundamental Technological Research, PAS

Date, Time
24.10, 15:00 - 16:00

Location
hybrid meetnig (room 16, close to Deans office), link (MSTeams) >>>

In the first part of my talk I will address a question: what happens when electrons’ motion becomes confined to one direction? Can we describe them? The answer, at least in the low energy limit, is the sine-Gordon model of Tomonaga-Luttinger liquid which allows to find all correlation functions no matter how strong correlations are, and the resulting Berezinskii-Kosterlitz-Thouless (BKT) phase diagram. In the second part I will move on to introduce a real material where such situation is realized. It belongs to a family of molybdenum purple bronzes, whose other members were early shown to be Peierls-CDW compounds, while the physics of the Li-compound has remained elusive. From the beginning of 21st century experimental evidence has been mounting, indicating that it may be a rare realization of Tomonaga-Luttinger liquid in a solid state material. However, the lowest energy physics does not obey this canonical picture and the origin of a mysterious upturn of resistivity was understood only few years ago [1]. Then I will move on to the most recent findings that directly probe the parent state of superconductivity [2]. We were able to show that the Li_0.9Mo₆O₁₇ is in fact in the higher symmetry state, right on the edge of Mott insulating region in the BKT picture. I will explain how the specific properties of Li_0.9Mo₆O₁₇ enabled us to measure directly the BKT renormalization group flow and what conclusions we were able to draw from that.

[1] Sci. Adv. 5, eaar8027 (2019)
[2] Science 382, 792-796 (2023)