Structural 130 K phase transition and emergence of a two-ion Kondo state in CeRhGa explored by Ga nuclear quadrupole resonance

Yamamoto, Shingo*; Fujii, Takuto*; Luther, S.*; Yasuoka, Hiroshi*; Sakai, Hironori   ; Brtl, F.*; Ranjith, K. M.*; Rosner, H.*; Wosnitza, J.*; Strydom, A. M.*; Khne, H.*; Baenitz, M.*

We have studied the microscopic magnetic properties, the nature of the 130 K phase transition, and the ground state in the recently synthesized compound CeRhGa by use of Ga nuclear quadrupole resonance (NQR). The NQR spectra clearly show an unusual phase transition at K, yielding a splitting of the high-temperature single NQR line into two well-resolved NQR lines, providing evidence for two crystallographically inequivalent Ga sites. The NQR frequencies are in good agreement with fully relativistic calculations of the band structure. Our NQR results indicate the absence of magnetic or charge order down to 0.3 K. The temperature dependence of the spin-lattice relaxation rate shows three distinct regimes, with onset temperatures at and 2 K. The temperature-independent , observed between and 2 K, crosses over to a Korringa process, , below 2 K, which evidences a rare two-ion Kondo scenario: The system evolves into a dense Kondo coherent state below 2.0 and 0.8 K probed by the two different Ga sites.