Research Highlights for Quantum Matter in High Magnetic Fields

Understanding the complex electronic behaviour of multiband superconductors relies on separating the contribution of different components that contribute to its conductivity. By measuring these components of the magnetoresitivity tensor both at very low temperatures using ultra-high magnetic fields up to 90 T and at high temperatures using fields up to 14 T we were able to disentangle to origin of different electronic bands.

A nematic state is a form of electronic order which breaks the rotational symmetries without changing the translational symmetry of the lattice, and this state may play an important role in understanding high temperature superconductivity. We have revealed the existence of a novel electronic state in an highly unconventional multiband superconductor, FeSe, from the evolution of its electronic structure from the high-temperature tetragonal phase into the electronic nematic phase using angle resolved photoemission spectroscopy (ARPES).

In iron-based superconductors, the interplay between nematicity, magnetism, and superconductivity is still not fully understood. Experimentally, the isoelectronic series FeSe1−xSx provides an ideal playground to tune different electronic ground states and to selectively investigate their mutual interplay. Here, we use high-resolution angle-resolved photoemission spectroscopy to compare the electronic structure of different single crystals in the tetragonal phase.

Cd3As2 is a candidate three-dimensional Dirac semimetal which has exceedingly high mobility and non-saturating linear magnetoresistance that may be relevant for future practical applications. Using ultra-high magnetic fields and a large range of temperatures we find that the nonsaturating linear magnetoresistance persists up to 65 T and it is likely caused by disorder effects, as it scales with the high mobility.