Spin-wave excitations of half-filled Kondo lattice model

The spin excitations in the antiferromagnetic phase of half-filled Kondo lattice model are studied by means of the decoupling approximation for spin Green's function. The spin-wave spectrum is calculated as a function of Kondo coupling, and this is used to calculate the thermodynamic quantities at low temperatures. The Neel temperature of the form T-N = 0.087J(2)ln(1/J) is obtained for the 3-dimensional case in the weak-coupling limit. It is pointed out that the ratio of the spin-wave velocity to the Neel temperature upsilon(s)/T-N is enhanced as the Kondo coupling becomes small, reflecting the long-range nature of effective interactions between localized spins.