Magnetic Studies of a 1-2-3 (Y,Gd)-Ba-Cu-Oxide Superconductor

摘要

Magnetic susceptibility measurements have been conducted on a sample of the ceramic superconductor (Y/sub 0.5/Gd/sub 0.5/) sub 1 Ba sub 2 Cu sub 3 O/sub y/ (YGBC, T/sub c/ = 92 K), the related compounds (Y/sub 0.5/La/sub 0.5/) sub 1 Ba sub 2 Cu sub 3 O/sub y/ (YLBC) and Y sub 1 Ba sub 2 Cu sub 3 O/sub y/ (YBC), and the starting oxides Y sub 2 O sub 3 , La sub 2 O sub 3 , and CuO. It is deduced that the S = 12 moment exhibited by the antiferromagnetic CuO (T/sub N/ = 560 K) is also present in YBC and YLBC and hence, presumably, in the YGBC. In the latter compound, any moment on the Cu is masked by the Gd's large moment (S = 72) which, according to both the susceptibility results and those of electron spin resonance studies which were also performed on the YGBC material, persists into the superconducting phase. Also reported are the results of vibrating sample magnetometer measurements taken under low-field-cycling conditions ((about Sub (plus or minus) 80 gauss, mostly in the Meissner flux-exclusion regime)) within the temperature range 4.2 K to about 87 K. (ERA citation 13:036866)