SKM 2021 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 18: Frustrated Magnets
TT 18.7: Talk
Thursday, September 30, 2021, 11:45–12:00, H7
Interplay of magnetism and dimerization in pressurized Kitaev compound β-Li2IrO3 — •Bin Shen, Anton Jesche, Maximilian Seidler, Friedrich Freund, Philipp Gegenwart, and Alexander A. Tsirlin — EP VI, EKM, University of Augsburg, Germany
Quantum spin liquids in a Kitaev honeycomb model, characterized by their quantum entanglement and fractionalized spin excitations, are subject to extensive studies recently. Here, we present magnetization measurements under pressure for β-Li2IrO3, the Kitaev material with the putative pressure-induced spin-liquid state, and construct the temperature-pressure phase diagram. A delicate interplay between magnetism and dimerization is revealed. β-Li2IrO3 undergoes incommensurate magnetic ordering at TN = 38 K at ambient pressure. Upon applying hydrostatic pressure, TN is almost pressure-independent before the transition abruptly disappears at around 1.5 GPa. At around 1.4 GPa, a signature of structural dimerization seen as a small step in the magnetic susceptibility appears at Td ≈ 120 K and shifts to higher temperatures upon further compression. Intriguingly, a low-temperature Curie-like upturn with the effective moment of about 0.7 µB is still observed. Using ab initio calculations, we interpret these results as the formation of a partially dimerized state that evades long-range magnetic order but features a fraction of magnetic Ir4+ sites.
Work supported by the German Research Foundation through the Sino-German Cooperation Group on Emergent Correlated Matter.