Antiferromagnetic phase transition in Bi 2Sr 2YCu 2O 8.37

Abstract

The antiferromagnetic (AF) phase transition of Bi 2Sr 2YCu 2O 8.37 was investigated by DC magnetic susceptibility (χ AF) and magnetic specific heat ( C mag) measurements. From the temperature dependence of χ AF, the exchange interaction J/ k B between Cu 2+-spins was derived as about 770 K and the AF transition temperature T N was obtained as about 340 K from the inflection point of χ AF; in the C mag data, an anomaly appeared at about 330 K, and magnetic entropy was estimated as 5.89 J/(mol-Cu 2+ K) from C mag/ T vs. T-curve. These results show that whole Cu 2+ spins of S = 1 2 order into antiferromagnetic state at T N = 330 ≈ 340 K.