Surface spin-glass behavior in La2/3Sr1/3MnO3 nanoparticles

The low-temperature magnetic and transport properties of La2/3Sr1/3MnO3 nan oparticles have been investigated. It is found that a surface spin-glass be havior exists in La2/3Sr1/3MnO3 nanoparticles, which undergo a magnetic tra nsition to a frozen state below 45 K. The low-temperature surface spin-glas s behavior exists even at the highest field used (H = 50 kOe). Moreover, th e spin-glass-like transition disappears for particles above 50 nm, In addit ion, the suppressed low-field magnetoconductivity (LFMC) observed at low te mperature for nanosized La2/3Sr1/3MnO3 is obviously lower than the expected upper limit of LFMC, 1/3, for polycrystalline manganites, which is propose d to arise from the higher-order tunneling through the insulating spin-glas s-like surface layers. (C) 2001 American Institute of Physics.