Ground-state phase diagram of the one-dimensional t-Js-Jτ model at quarter filling

We study the ground state of the one-dimensional "t-Js-Jτ model,"which is a variant of the t-J model with an additional channel degree of freedom. The model is not only a generalization of the t-J model but also an effective model of the two-channel Kondo lattice model in the strong-coupling region. The low-energy excitations and correlation functions are systematically calculated by the density matrix renormalization group method, and the ground-state phase diagram at quarter filling consisting of a Tomonaga-Luttinger liquid, spin-gap state, channel-gap state, insulator, and phase separation is determined. We find that weak channel fluctuations stabilize the spin-gap state, while strong channel fluctuations lead to the transition to the insulator.