Fermi surface reconstruction and multiple quantum phase transitions in the antiferromagnet CeRhIn 5

Conventional, thermally driven continuous phase transitions are described by universal critical behavior that is independent of microscopic details of a specific material. An analogous description is lacking for phase transitions that are driven at absolute zero temperature by a nonthermal control parameter. Classification of quantum-driven phase transitions is a fundamental but open problem that arises in diverse contexts and multiple classes of materials. Here we report the first observation, to our knowledge, of a sharp Fermi surface reconstruction while applying a strong magnetic field to suppress an antiferromagnetic transition to zero temperature. These experiments demonstrate that direct measurements of the Fermi surface can distinguish theoretically proposed models of quantum criticality and point to a universal description of quantum phase transitions. Conventional, thermally driven continuous phase transitions are described by universal critical behavior that is independent of the specific microscopic details of a material. However, many current studies focus on materials that exhibit quantum-driven continuous phase transitions (quantum critical points, or QCPs) at absolute zero temperature. The classification of such QCPs and the question of whether they show universal behavior remain open issues. Here we report measurements of heat capacity and de Haas–van Alphen (dHvA) oscillations at low temperatures across a field-induced antiferromagnetic QCP ( B c0 ≈ 50 T) in the heavy-fermion metal CeRhIn 5 . A sharp, magnetic-field-induced change in Fermi surface is detected both in the dHvA effect and Hall resistivity at B 0 * ≈ 30 T, well inside the antiferromagnetic phase. Comparisons with band-structure calculations and properties of isostructural CeCoIn 5 suggest that the Fermi-surface change at B 0 * is associated with a localized-to-itinerant transition of the Ce-4 f electrons in CeRhIn 5 . Taken in conjunction with pressure experiments, our results demonstrate that at least two distinct classes of QCP are observable in CeRhIn 5 , a significant step toward the derivation of a universal phase diagram for QCPs.