Berlin 2024 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 34: Focus Session: Dynamical Probes for Topological Magnetism

TT 34.2: Hauptvortrag

Mittwoch, 20. März 2024, 10:00–10:30, H 0104

Spectroscopic signatures of spin dynamics in spin-orbit-coupled magnets: resolving quantum spin liquids versus magnetically ordered phases — •Roser Valenti — Institute of Theoretical Physics, Goethe University Frankfurt, Frankfurt a.M., Germany

In the search for material realizations of quantum spin liquid phases, spin-orbit coupled magnets -- such as the so-called Kitaev materials -- have been intensively studied for the last decade. Quantum spin liquid states are characterized by the absence of long-range order even at zero temperature and the presence of exotic fractionalized excitations, in contrast to spin-wave excitations found in conventional magnets. Experimentally probing and theoretically modelling the signatures and topology of these excitations is a challenging task.

In this talk we will first review and discuss the microscopic modelling of spectroscopic signatures (Raman, INS, THz) of spin dynamics in spin-orbit coupled magnets, and we will then move to nonlinear spectroscopy. Nonlinear spectroscopy has been recently suggested as a potentially powerful tool to distinguish coherent fractionalized excitations from effects of disorder or finite lifetime, which are difficult to distinguish in linear response excitation continua. In this spirit, we will introduce methods to efficiently calculate nonlinear response functions numerically, and will present results for extended Kitaev models that are relevant for the description of real materials.

Work done in collaboration with David Kaib, Marius Möller and Wolfram Brenig and funded by the DFG /TRR288.