Evidence of existence of line nodes in superconducting gap in K₂Cr₃As₃ from specific heat masurements

We present low temperature specific heat measurements of the quasi-one-dimensional superconductor K₂Cr₃As₃ in magnetic fields up to 9T. A sharp specific-heat jump around T_C is observed, which is much larger than BCS prediction, indicating that this superconductor is in the strong-coupling regime. After subtracting the phonon and the Schottky contribution from the total specific heat, the obtained electronic specific heat at low temperatures is proportional to T²,and the field-dependent electronic specific heat is proportional to H^0.5. These results indicate that line nodes are present in the superconducting gap function of K₂Cr₃As₃.