The quantum critical point in CeRhIn_5: a resistivity study

TL;DR

This study investigates the pressure-temperature phase diagram of CeRhIn_5 under high magnetic fields, identifying a quantum critical point at 2.5 GPa through resistivity measurements, and compares its behavior with CeCoIn_5.

Contribution

It provides the first detailed resistivity-based evidence of a quantum critical point in CeRhIn_5 and analyzes the effects of pressure and magnetic field on its magnetic and superconducting states.

Findings

Quantum critical point at 2.5 GPa identified

Magnetic state persists up to highest fields in superconducting phase

Rapid collapse of antiferromagnetic order at critical pressure

Abstract

The pressure--temperature phase diagram of CeRhIn_5 has been studied under high magnetic field by resistivity measurements. Clear signatures of a quantum critical point has been found at a critical pressure of p_c = 2.5 GPa. The field induced magnetic state in the superconducting state is stable up to the highest field. At p_c the antiferromagnetic ground-state under high magnetic field collapses very rapidly. Clear signatures of p_c are the strong enhancement of the resistivity in the normal state and of the inelastic scattering term. No clear T2 temperature dependence could be found for pressures above T_c. From the analysis of the upper critical field within a strong coupling model we present the pressure dependence of the coupling parameter lambda and the gyromagnetic ratio g. No signatures of a spatially modulated order parameter could be evidenced. A detailed comparison with the magnetic field--temperature phase diagram of CeCoIn_5 is given. The comparison between CeRhIn_5 and CeCoIn_5 points out the importance to take into account the field dependence of the effective mass in the calculation of the superconducting upper critical field H_c2. It suggests also that when the magnetic critical field H_(0) becomes lower than H_c2 (0)$, the persistence of a superconducting pseudo-gap may stick the antiferromagnetism to H_c2 (0).