Two-band superconductivity and the effect of pressure in Ho 1− xDy xNi 2B 2C

Abstract

The effect of pressure on the superconductivity and magnetism in Ho 1− x Dy x Ni 2B 2C is studied both theoretically and experimentally. At P=0 GPa , the breakdown of the de Gennes scaling in this compound for superconducting transition temperatures that are less than the Néel temperature ( T c< T N) can be explained based on a phenomenological model of multiband superconductivity in an antiferromagnetic state. The validity of this model is further confirmed by transport experiments under pressure for x=0.1 and 0.4. In case of x=0.1 (T c <T N ) , increasing pressure decreases T c, but pressure has no influence on T c of the x=0.4 sample ( T c> T N). The pressure dependence of the upper critical field also supports the phenomenological theory of multiband superconductivity in an antiferromagnetic state.