COMPARISON OF THE ELECTRON-SPIN-RESONANCE LINEWIDTH IN MULTILAYERED CUMN SPIN-GLASSES WITH INSULATING VERSUS CONDUCTING INTERLAYERS

The temperature-dependent electron-spin-resonance linewidth DELTAH(T) may be used to investigate the effect of the geometry and interlayer m aterial on the magnetic properties of multilayered systems. We compare DELTAH(T) in CUMn/Al2O3 multilayers with previous measurements of CuM n/Cu samples. CuMn/Al2O3 samples with CuMn thicknesses, W(SG), from 40 angstrom to 20 000 angstrom obey the same form as the CuMn/Cu system, but show quantitative differences in the fitting parameters. The line widths of the CUMn/Al2O3 samples, even in the bulk, are systematically larger than the linewidths for the CuMn/Cu samples, suggesting that t he ESR linewidth is sensitive to differences in sample growth and stru cture. The value of the minimum linewidth decreases with decreasing Ws G in the CuMn/Al2O3 series, but remains constant in the CuMn/Cu series . Although susceptibility measurements of the freezing temperature T(f ) do not differentiate between samples with W(SG) greater-than-or-equa l-to 5000 angstrom, the ESR linewidth is sensitive to changes at large r length scales. This experiment emphasizes the importance of consider ing both the total sample thickness, as defined by the range of the co nduction electrons, and the spin-glass layer thickness in analyzing th e ESR linewidth in multilayers.