paper

Coexistence of metallic and nonmetallic properties in the pyrochlore Lu $_{2}$ Rh $_{2}$ O $_{7}$

arXiv:1903.00399 · doi:10.1038/s41535-019-0148-1

Abstract

Transition metal oxides of the $4 d$ and $5 d$ block have recently become the targets of materials discovery, largely due to their strong spin-orbit coupling that can generate exotic magnetic and electronic states. Here we report the high pressure synthesis of Lu $_{2}$ Rh $_{2}$ O $_{7}$ , a new cubic pyrochlore oxide based on $4 d^{5}$ Rh $^{4 +}$ and characterizations via thermodynamic, electrical transport, and muon spin relaxation measurements. Magnetic susceptibility measurements reveal a large temperature-independent Pauli paramagnetic contribution, while heat capacity shows an enhanced Sommerfeld coefficient, $I^^{3}$ = 21.8(1) mJ/mol-Rh K $^{2}$ . Muon spin relaxation measurements confirm that Lu $_{2}$ Rh $_{2}$ O $_{7}$ remains paramagnetic down to 2 K. Taken in combination, these three measurements suggest that Lu $_{2}$ Rh $_{2}$ O $_{7}$ is a correlated paramagnetic metal with a Wilson ratio of $R_{W} = 2.5$ . However, electric transport measurements present a striking contradiction as the resistivity of Lu $_{2}$ Rh $_{2}$ O $_{7}$ is observed to monotonically increase with decreasing temperature, indicative of a nonmetallic state. Furthermore, although the magnitude of the resistivity is that of a semiconductor, the temperature dependence does not obey any conventional form. Thus, we propose that Lu $_{2}$ Rh $_{2}$ O $_{7}$ may belong to the same novel class of non-Fermi liquids as the nonmetallic metal FeCrAs.

11 pages, 5 figures

Coexistence of metallic and nonmetallic properties in the pyrochlore Lu2​Rh2​O7​

Abstract

Coexistence of metallic and nonmetallic properties in the pyrochlore Lu $_{2}$ Rh $_{2}$ O $_{7}$