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TT: Fachverband Tiefe Temperaturen

TT 80: Correlated Electrons: Poster

TT 80.12: Poster

Thursday, March 21, 2024, 15:00–18:00, Poster E

Specific heat and magnetocaloric effect measurements as probe of field-induced states in the Cobalt based honeycomb compound BaCo2(AsO4)2 — •Sebastian Erdmann¹, Prashanta Mukharjee¹, Philipp Gegenwart¹, and Alexander A. Tsirlin² — ¹Experimentalphysik VI, Universität Augsburg, Germany — ²Felix Bloch Institute for Solid State Physics, Universität Leipzig, Germany

In recent years the honeycomb Kitaev model has attracted much interest, because it can be analytically solved and displays a quantum spin liquid (QSL) state. Realization of the Kitaev interaction requires spin-orbit magnetic moments. Thus, mainly 4d and 5d honeycomb materials, like α-RuCl3 and Na2IrO3 were studied in this context. However, recently the 3d⁷ Cobalt based honeycomb compounds such as BaCo2(AsO4)2, Na2Co2TeO6, and Na3Co2SbO6 were predicted as suitable alternatives. Although the Kitaev interaction may be weaker in these materials due to the weaker spin-orbit coupling, it was theoretical predicted, that the QSL state might be more accessible because of the easy suppression of the antiferromagnetic Heisenberg coupling. Among these materials BaCo2(AsO4)2 is a suitable candidate as it is free from structural imperfections and has a low critical field required to tune from the ordered to the paramagnetic state. We report specific heat and magnetic Grüneisen parameter measurements on BaCo2(AsO4)2 down to the millikelvin range and study the details of the H-T phase diagram. Several field-induced anomalies are observed, whose origin will be discussed.

Keywords: Kitaev