Fractionalization and Symmetry Breaking in Multichannel Kondo Lattices

Multichannel Kondo lattices describe the interaction between a lattice of local moments and multi-channel conduction bands and are used to model the rich physics that appears in heavy-fermion quantum materials. Previous studies indicate that the channel symmetry in these systems is spontaneously broken at low temperatures. Various patterns of channel-symmetry breaking can generate entanglement potentially useful for quantum information. Here, we use dynamical large-N method with a Schwinger boson representation of spins to go beyond both mean-field approximation and the independent-bath approximation mostly employed in previous works. This allows us to capture electronic dissipation and explore different regimes of screening in arbitrary lattices that reveal a spontaneous channel symmetry breaking under multichannel Kondo interaction. By going from one to infinite dimension we observe that channel asymmetry changes from being an irrelevant perturbation to a relevant one in the renormalization group sense. Additionally, in contrast to the perfectly screened 1D Kondo lattice, the over-screened Kondo case is gapless and the channel excitations are fractionalized into well-defined quasi-particle modes of fermionic holons. The full dispersion of low energy spinon and holon modes given by our numerics enables an effective theory and an analytical solution for the two-channel Kondo lattice in 1D to capture the physics in this critical phase.