Study of the superconducting gap in RNi2B2C (R = Y, Lu) single crystals by inelastic light scattering

Article

关键词: FLUX-LINE-LATTICE;    RAMAN-SCATTERING;    ENERGY-GAP;    ELECTRONIC-STRUCTURE;    SOFT PHONONS;    T-C;    LUNI2B2C;    YNI2B2C;    RNI(2)B(2)C;    EXCITATIONS;   

DOI  :  10.1103/PhysRevB.62.1291

来源: SCIE

【 摘 要 】

Superconductivity-induced changes in thr electronic Raman-scattering response were observed for the RNi2B2C (R =Y, Lu) system in different scattering geometries. In the superconducting state, 2 Delta-like peaks were observed in A(1g), B-1g, and B-2g spectra from single crystals. The peaks, in A,, and Bz, symmetries are significantly sharper and stronger than the peak in B-1g symmetry. The temperature dependence of the frequencies of the 2 Delta-like peaks shows typical BCS-type behavior, but the apparent values of the 2 Delta gap are strongly anisotropic for both systems. In addition, for both YNi2B2C and LuNi2B2C systems, there exists reproducible scattering strength below the 2 Delta gap which is roughly linear to the frequency in B-1g and B-2g symmetries. This discovery of scattering below the gap in nonmagnetic borocarbide superconductors, which are thought to be conventional BCS-type superconductors. is a challenge for current understanding of superconductivity in this system.

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