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Kitaev magnetism of iridium oxides and halides

Kitaev spin liquid remains an intriguing and elusive state of matter. In this talk, I will review iridate compounds as material prototypes of the Kitaev spin model, and focus on the possibility of using hydrostatic pressure for tuning these materials toward the anticipated spin-liquid state.

The A2IrO3 iridates are proximate to a dimerization transition that shortens the Ir-Ir distances and suppresses local magnetism. Both α- and β-Li2IrO3 undergo such a transition around 3.7 GPa, but the β-phase additionally shows a first-order transition around 1.4 GPa, where long-range magnetic order is suppressed without the loss of local magnetism. Using a combination of thermodynamic and local probes as well as band structure calculations, we suggest that above 1.4 GPa β-Li2IrO3 enters the classical spin liquid phase with part of the spins frozen below 15 K. This is accompanied by an increase in the off-diagonal anisotropy Γ and a decrease in the Kitaev exchange K, in contrast to the original expectations of enhancing Kitaev magnetism under pressure.

I will further present recent results on the hexahalide Ir-based antifluorite compounds K2IrCl6 and K2IrBr6, where large single crystals can be grown from the solution. These compound entail the frustrated face-centered cubic arrangement of the Ir4+ ions and may be proximate to the ideal jeff=½ state, although we detect symmetry lowering in K2IrBr6 as well as a soft rotary mode in K2IrCl6, suggesting the proclivity of these compounds to structural distortions. Magnetic transitions are accompanied by structural anomalies, suggesting a strong coupling between magnetism and lattice. Moreover, large single crystals render neutron-scattering experiments more feasible than in any other iridium compounds studied to date.

Seminar: Neutronen in Forschung und Industrie

Datum03.12.2018
Uhrzeit14:30 - 15:30 Uhr
OrtGarching / Physik Department
RaumHS 3
SprecherDr. Alexander Tsirlin, University of Augsburg
Veranstalter

TUM / MLZ


Kontakt

Ansprechpartner

Dr. Markos Skoulatos und Dr. Alexandros Koutsioumpas

E-Mail

Markos.Skoulatos@frm2.tum.de

URL

https://indico.frm2.tum.de/e/161

MLZ ist eine Kooperation aus:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Hereon> Helmholtz-Zentrum Hereon
Forschungszentrum Jülich> Forschungszentrum Jülich

MLZ ist Mitglied in:

LENS> LENSERF-AISBL> ERF-AISBL

MLZ in den sozialen Medien: