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Identifying quantum spin liquids in experiments is challenging due to several factors. Firstly, these systems lack long-range magnetic order, making them difficult to distinguish from disordered magnetic phases or paramagnetic states. Secondly, quantum spin liquids exhibit emergent phenomena, such as fractionalized excitations like Majorana fermions, which do not have direct analogs in classical or conventional quantum magnetism. While these novel excitations are challenging to detect and characterize experimentally, direct comparison of the experimental findings with theoretically computed dynamical responses in corresponding probes such as neutron scattering, Raman spectroscopy, phonon dynamics, or scanning tunneling microscopy allows for the identification of unique features in these responses which allows to distinguish quantum spin liquid behavior from other phenomena. In my talk, I will focus on potential identifications of quantum spin liquid behavior in Kitaev materials. In the exactly solvable Kitaev model, spin excitations are fractionalized into two types of quasiparticles: itinerant spinon-like excitations described by Majorana fermions and localized gapped Z2 fluxes. Our studies indicate that characteristic signatures of such spin fractionalization can be observed in phonon dynamics, such as the temperature and field evolution of sound attenuation measured in ultrasound experiments. Another example is the analysis of the dynamical response of the site-diluted Kitaev spin liquid, which reveals that defect-induced localized excitations and spin fractionalization can potentially be observed using scanning tunneling microscopy.

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Nathalia Perkins, University of Minnesota
Seminar Room of the Institute of Physics II
Contact: Simon Trebst