Amalia Coldea

Abstract:

The upper critical field of multi-band superconductors can be an essential quantity to unravel the nature of superconducting pairing and its interplay with the electronic structure. Here we experimentally map out the complete upper critical field phase diagram of FeSe for different magnetic field orientations at temperatures down to 0.3 K using both resistivity and torque measurements. The temperature dependence of the upper critical field reflects that of a multi-band superconductor and requires a two-band description in the clean limit with band coupling parameters favouring interband over intraband interactions. Despite the relatively small Maki parameter in FeSe of α ∼ 1.6, the multi-band description of the upper critical field is consistent with the stabilization of a FFLO state below T /Tc ∼ 0.3. We find that the anomalous behaviour of the upper critical field is linked to a departure from the single-band picture, and FeSe provides a clear example where multi-band effects and the strong anisotropy of the superconducting gap need to be taken into account.

Abstract:

This dataset is related to the publication entitled: "Resurgence of superconductivity and the role of the dxy hole band in FeSe1−xTex" to appear in Communication Physics. The data files are either ARPES data collected to the Diamond Light Source (.nxs files), ASCII files with the extracted paramaters (.dat) or structural files used as input in DFT calculations (.struct). The PDF files of each figures are provided.

Abstract:

This data set was created as a part of the transport and torque measurements to understand the behaviour of the upper critical field of FeSe. These data correspond to the publication with the same name entitled: Multi-band description of the upper critical field of bulk FeSe, by M. Bristow et al. to appear in Physical Review B. The measurements were performed as a function of magnetic fields at constant temperatures using a low temperature cryostat in Oxford and at the High Field Magnet Laboratory (HFML) in Nijmegen up to 35T. This data set contains ASCII files and the different folders and subfolders contain the files corresponding to particular figure and subfigure, respectively. The data were analysed using the WHH model (Phys. Rev.147, 295 (1966)) and the two-band model, as described in Phys. Rev. B 82, 184504 (2010). The Fermi surface was calculated using the Wien2k and using the experimental parameters and the .struct file is provided.