Quantum matter in high magnetic fields

Abstract:

We report magnetotransport studies in thin (<100nm) exfoliated films of Cu_xBi₂Se₃ and we detect an unusual electronic transition at low temperatures. Bulk crystals show weak superconductivity with T_c∽3.5K and a possible electronic phase transition around 200K. Following exfoliation, superconductivity is supressed and a strongly temperature dependent multi-band conductivity is observed for T<30K. This transition between competing conducting channels may be enhanced due to the presence of electronic ordering, and could be affected by the presence of an effective internal stress due to Cu intercalation. By fitting to the weak antilocalisation conductivity correction at low magnetic fields we confirm that the low temperature regime maintains a quantum phase coherence length L_φ > 100nm indicating the presence of topologically protected surface states.

Abstract:

These data were created by recording the transport behaviour on thin flakes devices at low temperatures and in magnetic field. These are all DAT files easily readable

Abstract:

These are the Raw data used to generate the figures related to the publication: "Evolution of the Fermi surface of the nematic superconductors FeSe1-xSx" by A. I. Coldea et al.

Abstract:

These data make up the figures of the paper with the same name to be published in Physical Review Materials. The data are raw .DAT file created mainly by measuring magnetization in magnetic field at different temperatures and analysing the raw data, as described in the paper.

Abstract:

Iron-based chalcogenides are complex superconducting systems in which orbitally-dependent electronic correlations play an important role. Here, using high-resolution angle-resolved photoemission spectroscopy, we investigate the effect of these electronic correlations outside the nematic phase in the tetragonal phase of superconducting FeSe1-xSx (x = 0; 0:18; 1). With increasing sulfur substitution, the Fermi velocities increase significantly and the band renormalizations are suppressed towards a factor of 1.5-2 for FeS. Furthermore, the chemical pressure leads to an increase in the size of the quasi-two dimensional Fermi surface, compared with that of FeSe, however, it remains smaller than the predicted one from first principle calculations for FeS. Our results show that the isoelectronic substitution is an effective way to tune electronic correlations in FeSe1-xSx, being weakened for FeS with a lower superconducting transition temperature. This suggests indirectly that electronic correlations could help to promote higher-Tc superconductivity in FeSe.