Bond-operator mean-field theory of the half-filled Kondo lattice model

Abstract

We present a bond-operator mean-field theory for the Kondo lattice model at half filling in two and three dimensions (3D). A continuous quantum phase transition from an antiferromagnetic to a spin-gapped singlet ground state is found at $J/t=1.505$ $(1.833)$ in $2\mathrm{D}$ $(3\mathrm{D}).$ Additionally we evaluate the quasiparticle dispersions as well as the staggered magnetic moment and provide a comparison with complementary numerical approaches.