Effect of hole-doping on the valence state and magnetic property in S = 1/2 spin-chain system LiCuVO 4

Abstract

The valence state and magnetic properties of hole-doped LiCuVO 4 are investigated. By analyzing the Cu 2 p core-level photoemission spectra, the holes are suggested to be introduced into Cu 2+ site in the formation of Cu 3+ ion. The calculation of effective moment also confirms the presence of nonmagnetic Cu 3+ ion which should be responsible for the decrease of high-temperature susceptibility after hole doping. At low temperature, the antiferromagnetic transition at 26 K and 2.3 K disappears due to the enhancement of Curie term. Magnetic hysteresis at 2 K shows that there exists a small ferromagnetic moment of 0.15 emu/g in Li 0.9CuVO 4.