The magnetic state of the Co-sublattice in Tb_(1-x)Y_xCo_2

摘要

The Tb_(1-x)Y_xCo_2 pseudobinary series has been studied by means of resistivity, magnetic susceptibility and neutron diffraction measurements. According to the neutron diffraction a long-range magnetic order in this system exists only for x < 0.8. In compounds with the yttrium concentration near x_c approx= 0.8 a short-range magnetic order and anomalies in the transport properties: maximal value of the residual resistivity and large magnetoresistance effect (about -30%) were observed. We have found that the concentration dependence of the residual resistivity #rho#_(res) for Tb_(1-x)Y_xCo_2 (as well as for other (R_(1-x)Y_x)Co_2 compounds) correlates with the variation of the coefficient #gamma# (linear term of the low-temperature specific heat). In vicinity of x_c where the Co-magnetic moment is unstable the maximums of #rho#_(res) and #gamma# can be associated with the large contribution from localized spin density fluctuations of d-electrons to both electrical resistivity and specific heat.