Quantum Fluctuations in the Non-Fermi Liquid System CeCo${}_2$Ga${}_8$ Investigated Using $\mu$SR

Abstract

Reduced dimensionality offers a crucial information in deciding the type of the quantum ground state in heavy fermion materials. Here we have examined stoichiometric CeCo${}_2$Ga${}_8$ compound, which crystallizes in a quasi-one-dimensional crystal structure with Ga-Ce-Co chains along the $c$-axis. The low-temperature behavior of magnetic susceptibility ($\chi \sim -\ln T$), heat capacity ($C_p/T\sim -\ln T$), and resistivity ($\rho \sim T^n$) firmly confirm the non-Fermi liquid ground state of CeCo${}_2$Ga${}_8$. We studied the low-energy spin dynamics of CeCo${}_2$Ga${}_8$ compound utilizing zero field (ZF-) and longitudinal field (LF-) muon spin relaxation ($\mu$SR) measurements. ZF-$\mu$SR measurement reveals the absence of long-range magnetic ordering down to 70 mK, and interestingly below 1 K, the electronic relaxation rate sharply rises, intimating the appearance of low energy quantum spin fluctuations in CeCo${}_2$Ga${}_8$.

6 pages, 2 figures