Magneto-volume coupling constant in itinerant-electron metamagnets

Abstract A pressure P dependence of the critical field B C of the metamagnetic transition from the paramagnetic state to ferromagnetic one in itinerant-electron metamagnets is discussed by the Landau energy expanded up to the sixth power of the magnetization, including the effect of the volume magnetostriction. It is shown that the magneto-volume coupling constant is given by the ratio between d B C /d P and the induced magnetic moment M ind by the magnetic field. From the observed values of these quantities, the magneto-volume coupling constant is estimated for Co(S,Se) 2 , Y(Co,Al) 2 , Lu(Co,M) 2 (M=Al, Ga), and U(Co,Fe)Al.