We have measured the Hall effect, magnetotransport, and magnetostriction on the field-induced phases of single-crystalline ${\mathrm{UPt}}_2{\mathrm{Si}}_2$ in magnetic fields up to 60 T at temperatures down to 50 mK, firmly establishing the phase diagram for magnetic fields $B\parallel a$ and $c$ axes. Moreover, for the $B\parallel c$ axis we observe strong changes in the Hall effect at the phase boundaries. From a comparison to band structure calculations utilizing the concept of a dual nature of the uranium $5f$ electrons, we propose that these represent field-induced topological changes of the Fermi surface due to at least one Lifshitz transition. Furthermore, we find a unique history dependence of the magnetotransport and magnetostriction data, indicating that the proposed Lifshitz-type transition is of a discontinuous nature, as predicted for interacting electron systems.

• Received 8 November 2016
• Revised 30 January 2017

DOI:https://doi.org/10.1103/PhysRevB.95.134422