Structural 130-K Phase Transition and Emergence of a Two-Ion Kondo State in HT-Ce${}_2$Rh${}_2$Ga Explored by ${}^{69,71}$Ga Nuclear Quadrupole Resonance

Abstract

We have studied the microscopic magnetic properties, the nature of the 130-K phase transition, and the ground state in the recently synthesized compound Ce${}_2$Rh${}_2$Ga by use of ${}^{69,71}$Ga nuclear quadrupole resonance (NQR). The NQR spectra clearly show an unusual phase transition at $T_t$ $\sim$ 130 K yielding a splitting of the high-temperature single NQR line into two clearly 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, 1/$T_1$, shows three distinct regimes, with onset temperatures at $T_t$ and 2 K. The temperature-independent 1/$T_1$, observed between $T_t$ and 2 K, crosses over to a Korringa process, 1/$T_1$ $\propto$ $T$, below $\sim$ 2 K, which evidences a rare two-ion Kondo scenario: the system goes into a dense Kondo coherent state at 2.0 and 0.8 K for the two different Ga sites.

12 pages, 7 figures

References in corpus (2)

• Kondo lattices with inequivalent local moments: Competitive vs. co-operative Kondo screening
• Successive magnetic transitions in heavy fermion superconductor Ce3PtIn11 studied by 115In nuclear quadrupole resonance