From extreme magnetoresistance to superconductivity

Figure caption: Unit-cell volume of LaBi as a function of pressure. The discontinuous drop at P ≈ 11 GPa corresponds to a structural phase transition from face-centered cubic to primitive tetragonal lattice as illustrated on the figure.
Figure caption: Unit-cell volume of LaBi as a function of pressure. The discontinuous drop at P ≈ 11 GPa corresponds to a structural phase transition from face-centered cubic to primitive tetragonal lattice as illustrated on the figure.

Extreme magnetoresistance (XMR) has been recently observed in a growing number of topological semimetals. Recent studies on (W/Mo)Te2 and (Zr/Hf)Te5 suggest that pressure suppresses the XMR and gives rise to superconductivity. To search for a relation between XMR and superconductivity, a research team used HPCAT facility to study the effect of pressure on LaBi. A disappearance of XMR, together with an appearance of superconductivity, is observed at a pressure of ~3.5 GPa, showing the pressure effect on XMR and superconductivity in LaBi. Different from other superconducting XMR materials, a pressure region of coexistence between superconductivity and XMR is observed in LaBi. The suppression of XMR in LaBi is accompanied by a sign change in the Hall coefficient RH from negative to positive. The change in the crystal structure is found to be responsible for the change in band structure and creates a region of band inversion in LaBi. The suppression of XMR is correlated with increasing zero-field resistance instead of decreasing in-field resistance. More in Tafti et al, Phys. Rev. B, 95, 014507, (2017)