Quantum Criticality in the Strongly Correlated CeRhIn₅

Tuson Park, Sungkyunkwan University

The strongly correlated compound CeRhIn₅ is a prototypical antiferromagnet with transition temperature T_N =3.8 K at ambient pressure [1]. When subjected to applied pressure, T_N initially increases, but starts to decrease above 5 kbar, where unconventional superconductivity is simultaneously induced. At a critical pressure of 17.5 kbar, T_N and T_c become equal and magnetism disappears above this pressure, suggesting a first-order-like transition under pressure [2]. Difficulty of understanding the strange metallic behaviors in the normal state at this pressure range has been resolved by recent discovery of hidden magnetic quantum critical point (QCP) in the superconducting phase [3]. In this talk we discuss nature of the hidden QCP. Anisotropy in the electrical resistivity of CeRhIn₅ was measured under pressure, which revealed disappearance of the anisotropy in the vicinity of the hidden QCP. When pressure is far away the critical point, the anisotropy is strongly enhanced. When combined with Fermi surface volume jump at this critical pressure [4], the isotropic scattering indicates realization of a local-type critical point in this compound, providing the first example of unconventional superconductivity in the non-SDW quantum critical metals [5].

References 

[1] H. Hegger et al., “Pressure-induced superconductivity in quasi-2D CeRhIn₅,” Phys. Rev. Lett. 84, 4986 (2000).

[2] T. Park et al. “Electronic duality in strongly correlated matter,” Proc. Nat. Acad. Sci. (USA) 105, 6825 (2008).

[3] T. Park et al., “Hidden magnetism and quantum criticality in the heavy fermion superconductor CeRhIn₅,” Nature 440, 65 (2006).

[4] H. Shishido et al., “A drastic change of the Fermi surface at a critical pressure in CeRhIn₅: dHvA study under pressure,” J. Phys. Soc. Jpn. 74, 1103 (2005).

[5] T. Park et al., “Isotropic quantum scattering and unconventional superconductivity,” Nature 456, 366 (2008).