Abstract
The magnetic field dependence of the low-temperature specific heat (LTSH) and I-V characteristics measurements on RuSr 2 EuCu 2 O 8 were systematically carried out. It is found that the linear-T term γ decreases with increasing H, in contrast to the predicted result for the clean d-wave superconductivity. This finding suggests that the interaction between quasiparticles and magnons be weakened by magnetic field. In addition, the LTSH data exhibits a remarkably large T 2 term for both H = 0 and H ≠ 0. The T 2 term might be predominately associated with weak ferromagnetism in the Ru sublattice. Furthermore, the effective flux pinning energy E(H, T) determined from fitting the nonlinear region of the I-V curves follows a power-law dependence on magnetic field with an exponent close to -0.5 at a fixed temperature, indicating that the vortex lines of RuSr 2 EuCu 2 O 8 is quasi-two-dimensional. © 2007 Elsevier B.V. All rights reserved.