Magnetic and transport properties of layered LixCo0.5RhO3

Band insulator Li1.5Co0.5RhO3 has been synthesized, in which Co and Rh atoms are partially disordered in the two-dimensional Co1/3Rh2/3O2 layer. Measurements of magnetic susceptibility indicate that Co(III) and Co(III) are both diamagnetic with low-spin configurations. The electrical resistivity and thermopower reveal one-dimensional variable-range hopping below T1=320 K and above T2=630 K. Charges introduced by Li extraction down to x = 0.75 in LixCo0.5RhO3 yield the systematic decreases in resistivity and T1, but the magnetic ordering is observed at TN=30 K, which can be accounted for by spin-orbital coupling with antiferromagnetic interaction.