High pressure studies on YNi₂B₂C and LuNi₂B₂C: ADXRD, thermoelectric power, resistivity, and electronic structure

The electronic and structural behaviour of YNi₂B₂C and LuNi₂B₂C at high pressures were investigated by electrical resistivity, thermoelectric power (TEP), and angle dispersive X-ray diffraction measurements and by electronic band structure calculations. The pressure variation of TEP shows a peak around 2 GPa in YNi₂B₂C. However, the X-ray powder diffraction does not show any structural transition up to 16.4 GPa. The equation of state of YNi₂B₂C yielded a relatively high bulk modulus of 200 GPa. The observed peak in TEP and the pressure variation of the superconducting transition temperature can be correlated with different components of the electronic density of states. The universal equation of state shows deviation from linearity around 1.5 GPa pressure and correlates well with the TEP peak.