Non-Fermi liquid, unscreened scalar chirality and parafermions in a frustrated tetrahedron Anderson model

摘要

We investigate a four-impurity Anderson model where localized orbitals arelocated at vertices of a regular tetrahedron and find a novel fixed point inaddition to the ordinary Fermi liquid phase. That is characterized byunscreened scalar chirality of a tetrahedron. In this phase, parafermionsemerges in the excitation spectrum and quasiparticle mass diverges as 1/|Tlog^3 T| at low temperatures (T). The diverging effective mass is amanifestation of singular Fermi liquid states as in the underscreened Kondoproblem. Between the two phases, our Monte Carlo results show the existence ofa non Fermi liquid critical point where the Kondo effects and the intersiteantiferromagnetic interactions are valanced. Singular behaviors are prominentin the dynamics and we find that the frequency (omega) dependence of theself-energy (Sigma) is the marginal Fermi liquid like, -Im Sigma \sim |omega|.