Institut für Festkörperphysik



Superconductivity and magnetism in quaternary borocarbides and boronitrides

The discovery of rare-earth nickel borocarbide und boronitride superconductors, RT2B2C and (LaN)3Ni2B2 triggered an intense worldwide research activity which revealed a number of extraordinary features:
  • Peculiarities of the electron-phonon interaction,
  • Fermi-surface-nesting and multiband-characteristics,
  • nonlocality effects in the superconducting state,
  • Anisotropy of the upper critical field,
  • Peculiarities of the fluxline lattice,
  • interplay phenomena of superconductivity and magnetism.

A very important aspect of this class of compounds is their layered structure (see figure) with some analogy to MgB2 (Tc~ 40 K) and the high Tc cuprates. The boroarbides have been intensively investigated by many groups and new theoretical efforts in the field of multi-band and unconventional superconductivity have been stimulated. The boronitride (LaN)3Ni2B2 on the other hand has been subject of just a few investigations, because of their challenging preparation, though it suites as an archetype layered superconductor with a natural ABABAB... heterostructure. We currently work on the optimisation of the preparation of single phase (LaN)3Ni2B2 material and search related boronirtide compounds with magnetic rare-earth elements.

FWF-Project: P16250-Phy

Fig.1: Structure of borocarbide/nitride superconductors
Contact: H. Michor, G. Hilscher