Magnetization study in the superconducting mixed state of URu2Si2

Magnetization measurements of a heavy fermion compound URu2Si2 have been performed in the superconducting state. Broad peak structure of the irreversible magnetization was observed around 50 kOe for H parallel to n. The Ginzburg-landau parameter obtained from the equilibrium magnetization slightly decreases for H parallel to c with decreasing temperature, suggesting the presence of the paramagnetic suppression of the superconductivity. However, the suppression is not so large as expected from the H-c2(T) curve. Thermodynamic critical field appears to show unusual temperature dependence. (C) 2000 Elsevier Science B.V. All rights reserved.