Two-dimensional correlation analysis of raman spectra of superconducting YNi₂B₂C

This paper demonstrates the potential of two-dimensional (2D) correlation analysis for characterizing the effect of magnetic fields on the Raman spectra of superconducting YNi₂IB₂C single crystal. The synchronous 2D Raman correlation spectrum from the magnetic field-dependent Raman spectra of superconducting YNi₂B₂ C single crystal reveals that the two prominent peaks at 204 and 42 cm^-1 are strongly positively correlated, in accordance with the BCS theory. Moreover, the superconducting gap peak at 42 cm^-1 shows much greater variation in intensity than the phonon peak at 204 cm^-1. The corresponding asynchronous 2D Raman correlation spectrum suggests that the decrease in the intensity of the phonon peak at 204 cm^-1 occurs before that of the gap peak at 42 cm^-1 with the applied magnetic field.