Quantum Monte Carlo Simulation of Frustrated Kondo Lattice Models

TL;DR

This paper develops a sign-problem-free quantum Monte Carlo method for frustrated Kondo lattice models, revealing novel phases like a nematic partial Kondo screened state.

Contribution

It introduces a new auxiliary field quantum Monte Carlo algorithm applicable to frustrated Kondo systems, enabling exploration of complex quantum phases.

Findings

Identification of a partial Kondo screened phase breaking lattice rotation symmetry.

Demonstration of a sign-problem-free simulation approach for frustrated Kondo models.

Observation of multiple competing phases including Kondo insulator and antiferromagnetic order.

Abstract

The absence of negative sign problem in quantum Monte Carlo simulations of spin and fermion systems has different origins. World-line based algorithms for spins require positivity of matrix elements whereas auxiliary field approaches for fermions depend on symmetries such as particle-hole. For negative-sign-free spin and fermionic systems, we show that one can formulate a negative-sign-free auxiliary field quantum Monte Carlo algorithm that allows Kondo coupling of fermions with the spins. Using this general approach, we study a half-filled Kondo lattice model on the Honeycomb lattice with geometric frustration. In addition to the conventional Kondo insulator and anti-ferromagnetically ordered phases, we find a partial Kondo screened state where spins are selectively screened so as to alleviate frustration, and the lattice rotation symmetry is broken nematically.