Non-monotonic pressure dependence of high-field nematicity and magnetism in CeRhIn 5

CeRhIn5 provides a textbook example of quantum criticality in a heavy fermion system: Pressure suppresses local-moment antiferromagnetic (AFM) order and induces superconductivity in a dome around the associated quantum critical point (QCP) near pc ≈ 23 kbar. Strong magnetic fields also suppress the AFM order at a field-induced QCP at Bc ≈ 50 T. In its vicinity, a nematic phase at B* ≈ 28 T characterized by a large in-plane resistivity anisotropy emerges. Here, we directly investigate the interrelation between these phenomena via magnetoresistivity measurements under high pressure. As pressure increases, the nematic transition shifts to higher fields, until it vanishes just below pc. While pressure suppresses magnetic order in zero field as pc is approached, we find magnetism to strengthen under strong magnetic fields due to suppression of the Kondo effect. We reveal a strongly non-mean-field-like phase diagram, much richer than the common local-moment description of CeRhIn5 would suggest. Multiple quantum critical behaviors exist in the heavy fermion material CeRhIn5, but their interrelation is less studied. Here, Helm et al. investigate the interrelation of two quantum critical points and other relevant orders, revealing a strongly non-mean-field-like phase diagram.