Evidence of dimensional crossover of the spin-glass transition in thin<i>Cu</i>Mn multilayers

Abstract

We have used high-quality ${\mathrm{Cu}}_{92}$${\mathrm{Mn}}_{8}$/${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ multilayers to investigate the shift in temperature and the change in scaling behavior of the spin-glass transition as a function of the layer thickness. In the thinnest CuMn layers (60 and 88 \AA{}), the spin-glass exponents determined from the nonlinear susceptibility shift to new values, distinctly different from those for the bulk. These exponents are consistent with numerical studies of 2D spin-glass systems, suggesting that a 3D to 2D crossover occurs.