Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 12: Correlated Electrons: Materials

TT 12.8: Vortrag

Dienstag, 6. September 2022, 11:30–11:45, H22

Charge-carrier properties near the bandwidth-controlled Mott transition in layered organic conductors probed by magnetic quantum oscillations — •Mark V. Kartsovnik¹, Sebastian Oberbauer^1,2, Shamil Erkenov^1,2, Werner Biberacher¹, and Natalia D. Kushch¹ — ¹Walther-Meißner-Institut, Garching, Germany — ²Technische Universität München, Garching, Germany

Despite the great amount of work devoted to the Mott metal-insulator transition (MIT), some key theoretical predictions in this field are still awaiting experimental verification. In particular, there is no clarity about the exact behavior of the quasiparticle mass renormalized by many-body interactions, or about the pseudogap formation in the metallic ground state close to the bandwidth-controlled first-order MIT. Here we address these issues by employing organic κ-type salts as exemplary quasi-2D Mott systems and gaining direct access to their charge carrier properties via magnetic quantum oscillations. We trace the evolution of the effective cyclotron mass as the conduction bandwidth is tuned very close to the MIT by means of precisely controlled external pressure. We find that the sensitivity of the mass renormalization to subtle changes of the bandwidth strongly exceeds the theoretical predictions and is even further enhanced upon entering the transition region where the metallic and insulating phases coexist. On the other hand, even at this very edge of stability of the metallic ground state its Fermi surface remains fully coherent.