Mechanism of magnetic exchange interactions in europium monochalcogenides

Using a combination of local-spin-density and Hubbard 1 approximations, we study the mechanism of exchange interaction in EuX (X = O, S, Se and Te). We reproduce known experimental results with regard to bulk modulus, critical pressure for structural phase transition, magnetic ordering temperature, spin-wave dispersions, as well as momentum-and temperature-dependent band shift. Our numerical results show a pressure-induced competition between the hybridization-enhanced exchange interaction and Kondo-like coupling in EuO. Possible ways to enhance T-c are discussed.