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Universal zero-frequency Raman slope in a d-wave superconductor

W. C. Wu·J. P. Carbotte
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Abstract

It is known that for an unconventional superconductor with nodes in the gap, the in-plane microwave or dc conductivity saturates at low temperatures to a universal value independent of the impurity concentration. We demonstrate that a similar feature can be accessed using channel-dependent Raman scattering. It is found that, for a $d_{x^2-y^2}$-wave superconductor, the slope of low-temperature Raman intensity at zero frequency is universal in the $A_{1g}$ and $B_{2g}$ channels, but not in the $B_{1g}$ channel. Moreover, as opposed to the microwave conductivity, universal Raman slopes are sensitive not only to the existence of a node, but also to different pairing states and should allow one to distinguish between such pairing states.

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W. C. Wu, J. P. Carbotte. 1997-08-11. Universal zero-frequency Raman slope in a d-wave superconductor. https://doi.org/10.1103/physrevb.57.r5614

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