Competition Between Antiferromagnetic Order and Spin-Liquid Behavior in   the Two-Dimensional Periodic Anderson Model at Half-Filling
  We study the two-dimensional periodic Anderson model at half-filling using quantum Monte Carlo (QMC) techniques. The ground state undergoes a magnetic order-disorder transition as a function of the effective exchange coupling between the conduction and localized bands. Low-lying spin and charge excitations are determined using the maximum entropy method to analytically continue the QMC data. At finite temperature we find a competition between the Kondo effect and antiferromagnetic order which develops in the localized band through Ruderman-Kittel-Kasuya-Yosida interactions. 
M. Vekic, J.W. Cannon, D.J. Scalapino, R.T. Scalettar, and R.L. Sugar