Antiferromagnetic Kondo lattice compound Ce2O2Bi with anti-ThCr2Si2-type structure

Abstract

Abstract The transport, magnetic and thermodynamic properties of the cerium oxide bismuth compound Ce2O2Bi are systematically investigated in a wide temperature regime. The compound crystallizes in the anti-ThCr2Si2-type structure consisting of a separated Bi2− square net layer between the CeO layers. In the high temperature regime 200–300 K, the compound shows the conventional metallic behavior and localized 4 f electrons of Ce3+ ions. In the low temperature regime 15–30 K, the resistivity increases with a logarithmic temperature dependence, accompanied with the negative magnetoresistance and a low carrier density. Further decreasing temperature, the resistivity drops rapidly below 6.2 K, signaling an antiferromagnetic ordering transition within the Kondo phase. Both susceptibility and specific heat display a similar transition around the same temperature, accompanied with a reduced magnetic entropy. A large Sommerfeld coefficient ∼ 336 mJ/mol K2 is obtained by fitting the specific heat data and no superconductivity is observed down to 0.3 K. All these observations suggest that Ce2O2Bi is a rare low carrier density Kondo lattice compound whose interlayer hybridization between 4 f electrons of Ce3+ ions and conduction 6 p electrons of Bi2− ions plays a crucial role.