SKM 2023 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 10: Correlated Electrons: Other Materials

TT 10.6: Talk

Monday, March 27, 2023, 16:15–16:30, HSZ 204

Effect of anion substitution on the Mott insulating instability in the organic conductors κ-(BEDT-TTF)₂X studied by magnetic quantum oscillations — •Shamil Erkenov^1,2, Florian Kollmannsberger^1,2, Werner Biberacher¹, Ilya Sheikin³, Toni Helm⁴, Natalia Kushch¹, Rudolf Gross^1,2, and Mark Kartsovnik¹ — ¹Walther-Meißner-Institut, Garching, Germany — ²Technische Universität München, Garching, Germany — ³Laboratoire National des Champs Magnétiques Intenses, Grenoble, France — ⁴Hochfeld-Magnetlabor Dresden, HZDR, Dresden, Germany

The layered organic charge-transfer salts κ-(BEDT-TTF)₂X have been extensively employed as model systems for studying the Mott metal-insulator transition. The insulating instability in these materials is very sensitive to external pressure and to minor chemical changes, e.g., variation of the insulating anion. The anion substitution is broadly believed to act similarly to pressure, leading to a modification of the correlation strength ratio U/t. However, recent first-principles band-structure calculations [1] suggest that anion substitution in κ salts influences the ground state chiefly through the spin-frustration effect by changing the transfer-integral anisotropy ratio t^′/t rather than through U/t. Here we report on comparative studies of magnetic quantum oscillations in the salts with X = NCS, Cl, and Br, aiming at disentangling the roles of the electronic correlations and spin frustration in the insulating instability within this family.

[1] T. Koretsune and C. Hotta, Phys. Rev. B 89, 045102 (2014).