On the temperature dependence of coercivity and exchange biasing field in La-Ca-Mn-O ferromagnetic/antiferromagnetic multilayers

Two series of exchange-coupled [La1-xCaxMnO3(4nm)/La1-xCaxMnO3 (4nm)](15) multilayers (one with constant y = 0.67 while x = 0.33, 0.4, 0.48, and the other with constant x = 0.4 while y = 0.52, 0.75) were used to investigate the effect of the field cooling on both, the exchange-biasing field (H-EB) and the coercivity (H-e). Large magnetothermal irreversibilities result in spin-glass-like M(T) curves. Exchange bias appears below a blocking temperature T-B approximate to 70 K. Between 5 and 70 K, the M(H) loops exhibit an asymmetry between the magnetization reversal from + M to -M and that from -M to +M, which seems to depend strongly on the domain structure in the FM layers. (C) 2002 Elsevier Science B.V. All rights reserved. Journal of Magnetism and Magnetic Materials