Quantum criticality enabled by entwined degrees of freedom

Strange metals appear in a wide range of correlated materials. Electronic localization-delocalization and the expected loss of quasiparticles characterize beyond-Landau metallic quantum criticality and the associated strange metallicity. Typical settings involve local spins. Systems that contain entwined degrees of freedom offer new platforms for this physics. Here we study [1] the fate of an SU(4) spin-orbital Kondo state in a multipolar Bose-Fermi Kondo model, an effective description of a multipolar Kondo lattice. We show that at zero temperature a generic trajectory in the parameter space contains two quantum critical points, which are associated with the destruction of Kondo effect in the orbital and spin channels respectively. Their asymptotically exact results reveal an overall phase diagram, provide the understanding of puzzling recent experiments of a multipolar heavy fermion metal [2], and point to a means of designing new forms of quantum criticality in a variety of strongly correlated systems.



Work in part supported by by the NSF (DMR-2220603)



[1] C.-C. Liu, S. Paschen, and Q. Si, PNAS 120, e2300903120 (2023). https://doi.org/10.1073/pnas.2300903120



[2] V. Martelli et al., Proc. Natl. Acad. Sci. U.S.A. 116, 17701 (2019).