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Kondo signatures in defected Dirac spin liquids: Non-Abelian bosonization after Chern-Simons fermionization

by Huanhuan Jiang, Feilong Luo, Yilin Wang, Peng Song, and Rui Wang

Submission summary

Authors (as registered SciPost users):

Peng Song

Abstract

The quantum impurity, which serves as in-situ probe of the thermal baths, is a prominent topic in materials research. Its application to quantum spin liquids has attracted great interest in last decades. However, the comprehensive understanding of the quantum impurity effects in quantum spin liquids is still an open question, due to the complicated gauge fluctuations and the strong-correlation between the fractionalized excitations and the impurity. Here, we propose a general method, a combination of the Chern-Simons fermionization and the Wess-Zumino-Witten theory. Our method shows that quantum spin liquids with local defects can induce emergent impurity phenomena, and provides a systematic solution to the quantum impurity problem in an important class of quantum spin liquids, i.e., the Dirac spin liquids. Under the Chern-Simons fermionization, the gauge fluctuations are apparently suppressed, and the strong-correlation between the fractionalized excitations and the impurity can be exactly solved by the non-Abelian bosonization. Consequently, the Fermi liquid and non-Fermi liquid fixed point as well as the crossover between them are identified, respectively, depending on the relevance of the impurity scattering among the Dirac valleys. The obtained fixed points lead to several new experimental fingerprints for Dirac spin liquids, including a Kondo-induced magneto-thermal effect, a non-monotonous thermal conductivity during the crossover, and an anisotropic spin correlation function. These findings provide a theoretical framework as well as the experimental guidance to explore novel Kondo phenomena in quantum spin liquids.