Abstract
The newly designed ( as well as rare-earth atom) materials based on quasi-two-dimensional bismuth layers provide a suitable playground to address the physics of Dirac fermions, in connection with magnetism and structural changes. Here, we perform an optical investigation as a function of temperature of , which reveals a vestigial linear frequency-dependent behavior of the optical conductivity in the midinfrared, ascribed to electronic interband transitions involving Dirac bands. Furthermore, we uncover optical signatures for a partial gapping of the Fermi surface, for energy scales up to 0.2 eV, at the onset of the spin reorientation transition which also manifests as an anomaly in the dc transport data. This may reveal the inclination towards a Fermi surface instability in topological materials, possibly related to a density-wave order.
- Received 15 May 2019
DOI:https://doi.org/10.1103/PhysRevB.100.041107
©2019 American Physical Society