Rotational tuning of Hc2 anomalies in ErNi2B2C: Angular-dependent superzone gap formation and its effect on the superconducting ground state

Abstract

ErNi2B2C is a member of the RNi2B2C family of magnetic superconductors, with Tc≈11 K and TN≈6 K. For magnetic fields applied along the magnetically hard c axis, the upper critical field Hc2 manifests a clear, sharp local maximum at TN. For magnetic fields applied within the basal plane, features in Hc2 are less distinct and there are field induced changes in the local magnetic ordering. In order to address the relationship between Hc2 and local moment order, anisotropic magnetic and transport measurements on single crystals of ErNi2B2C will be presented. In particular, detailed H−T phase diagrams for different orientations of the applied field, as well as possible evidence of a superzone gap formation at the antiferromagnetic phase transition and its effect on anisotropic upper critical field, will be discussed. The anomaly in Hc2 as well as sharp features in the normal-state resistivity can be tuned by changing the orientation of the applied field. This is consistent with tuning in and out of the 0.55a* magnetically ordered, superzone gapped phase.

Source-reported materials — not catalogue approval

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