Unlike the widely studied s-type two-gap superconductor MgB2, the chemically similar compounds ZrB2 and HfB2 do not superconduct above 1 K. Yet, it has been shown that small amounts of self- or extrinsic doping (in particular with vanadium), can induce superconductivity in these materials. Based on results of different macro- and microscopic measurements, including magnetometry, nuclear magnetic resonance (NMR), resistivity, and muon-spin rotation (μSR), we present a comparative study of Zr0.96V0.04B2 and Hf0.97V0.03B2. Their key magnetic and superconducting features are determined and the results are considered within the theoretical framework of multiband superconductivity proposed for MgB2. Detailed Fermi surface (FS) and electronic structure calculations reveal the difference between MgB2 and transition-metal diborides.
@article{arxiv.1703.03253,
title = {Doping-induced superconductivity of ZrB$_2$ and HfB$_2$},
author = {N. Barbero and T. Shiroka and B. Delley and T. Grant and A. J. S. Machado and Z. Fisk and H. -R. Ott and J. Mesot},
journal= {arXiv preprint arXiv:1703.03253},
year = {2017}
}