P1: Non-thermal photoinduced phase transitions in Mott based quantum materials

• Applicant: Professor Dr. Martin Eckstein
• Subject Area: Theoretical Condensed Matter Physics ; Experimental Condensed Matter Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 531215165

Mott insulators are materials which band theory would predict to be metallic, but which are insulating due to strong electron-electron interactions. Correlated electron systems at the brink of the Mott transition exhibit strong interactions between spin, orbital, charge, and lattice excitations, with potential technological applications towards ultrafast nonlinear devices. They provide an ideal platform to achieve light-induced control over complex functionalities along the main goals of this research unit: (i) Strongly correlated systems are ideal candidates in the search for unconventional hidden phases, i.e., states which cannot be reached along standard thermodynamic pathways. Focusing on the paradigmatic Mott material Chromium-doped V2O3, we aim to uncover the non-thermal free energy landscape and identify optimal ultrafast switching pathways between metallic, insulating, and magnetically ordered states, using THz/mid-IR/optical pump-probe spectroscopy and microscopic modelling, complemented by time- and angle-resolved photoemission spectroscopy (ARPES) experiments which are performed by other projects of this research unit. (ii) The Mott gap limits heating under laser irradiation, so that control of the spin and orbital physics should become possible using low energy (below bandgap) photons. Within a class of 1D Mott insulators we will explore the interplay of magnetic and lattice dynamics driven by classical and quantum light. Jointly with other projects of this research unit, we thereby aim to eventually realize nontrivial Floquet states in a quantum material.

• DFG Programme: Research Units
• Subproject of: FOR 5750: Optical Control of Quantum Materials (OPTIMAL)
• International Connection: Switzerland
• Partner Organisation: Schweizerischer Nationalfonds (SNF)
• Cooperation Partner: Dr. Elsa Abreu