ROBUST FERMI-SURFACE TOPOLOGY OF CeRhIn₅ IN HIGH MAGNETIC FIELDS

Sanu Mishra and Ilya Sheikin, LNCMI Grenoble, Tobias Förster, HLD Dresden, and Alix McCollam, HFML Nijmegen.

Rare-earth-based materials are now widely recognized as an ideal playground for exploration of the fascinating physics that develops around a quantum critical point (QCP). In Ce-based compounds, such a QCP typically separates an antiferromagnetic (AFM) state from a nonmagnetic ground state. In spite of numerous experimental investigations of such systems near a QCP, the details of what drives the QCP remain the subject of much theoretical debate. CeRhIn₅ is one of the best-studied heavy-fermion materials. This AFM compound with T_N = 3.8 K can be tuned to a QCP by pressure, chemical substitution, and magnetic field. Several de Haas–van Alphen (dHvA) experiments evidence localized f electrons of CeRhIn₅ at ambient pressure. As the critical pressure for the suppression of antiferromagnetism, P_c = 2.3 GPa, is reached, all dHvA frequencies observed below this pressure change discontinuously, signaling an abrupt Fermi-surface (FS) reconstruction as a consequence of f-electron delocalization. Recent results obtained at high magnetic fields suggested a unique behavior in CeRhIn₅. A field-induced QCP was reported to occur at the critical field B_c ≈ 50 T. An electronic-nematic phase transition was observed at B* ≈ 30 T and attributed to an inplane symmetry breaking. Finally, the emergence of additional dHvA frequencies was observed at B* and interpreted as a field-induced FS reconstruction associated with f-electron delocalization. This result is surprising given that magnetic fields are generally expected to localize the f electrons. To resolve this controversial issue, researchers from the EMFL laboratories in Grenoble, Dresden, and Nijmegen, together with their Japanese colleagues, performed a comprehensive dHvA study of CeRhIn₅ using both static (up to 36 T) and pulsed (up to 70 T) magnetic fields. Several dHvA frequencies were found to gradually emerge at high fields as a result of magnetic breakdown (Figure). Among them is the theoretically predicted ᵦ₁ branch, not observed so far. Comparison of the angle-dependent dHvA spectra with those of the non-4f compound LaRhIn₅ and with band-structure calculations evidence that the Ce 4f electrons in CeRhIn₅ remain localized up to 70 T. This rules out any FS reconstruction, either at the suggested nematic phase transition at B* or at the putative QCP at B_c. These results demonstrate the robustness of the FS and the localized nature of the 4f electrons inside and outside of the AFM phase.

Figure: FFT spectra of the static-field dHvA oscillations in CeRhIn₅. The inset shows the evolution of the dHvA frequencies with field obtained from pulsed (circles) and static (triangles) field measurements.

Robust Fermi-Surface Morphology of CeRhIn₅ across the Putative Field-Induced Quantum Critical Point, S. Mishra, J. Hornung, M. Raba, J. Klotz, T. Förster, H. Harima, D. Aoki, J. Wosnitza, A. McCollam, and I. Sheikin, Phys. Rev. Lett. 126, 016403 (2021).

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.016403

Contact: ilya.sheikin@lncmi.cnrs.fr