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Small angle neutron scattering experiments have been carried out in the mixed state to determine the values and anisotropy of the penetration depth and coherence length in the superconductor β-PdBi2. The distortion of the vortex lattice observed on changing the magnetic field direction suggests that the a–c anisotropy of penetration depth in β-PdBi2 is small. With the magnetic field applied along the c-axis, we estimated the magnitudes of the penetration depth and coherence length by analyzing the magnetic field dependence of the neutron scattering intensity from the vortex lattice. The estimated superconductor parameters are consistent with the upper critical field obtained from the magnetization measurement. [ABSTRACT FROM AUTHOR]

Specific heat and small-angle neutron scattering measurements have been performed on the superconductor β-PdBi2. Whereas models with a uniform gap do not yield an adequate description of the temperature-dependent specific heat and the temperature and magnetic field dependence of the SANS intensity, fits to a heuristic model with two gap parameters agree well with both data sets. The fact that two parameters are required indicates a momentum-dependent gap anisotropy and/or gaps of different magnitude on different Fermi surface sheets. Fits to this model indicate that the ratio of the two gap parameters increases as a function of increasing field. [ABSTRACT FROM AUTHOR]