The waiting time effect in spin glass thin films

Large finite size effects are well known in spin glass multilayer films (Phys. Rev Lett., vol.59, 22, 1987). These effects are likely due to the Lower Critical Dimension (LCD) of the spin glass state lying between 2D and 3D. Previous dynamic studies have shown that a 3 nm multilayer film displays significantly faster dynamics than bulk samples, and a likely T = 0 K fixed point (Phys. Rev. B, vol. 40, 1, 1989). In this study we use High sensitivity DC SQUID magnetometry to probe the waiting time effect in multilayer spin glass films with spin glass layer thicknesses between 1 nm and 10 nm. The waiting time effect is an important signature of the spin glass phase and has been used extensively in the past to analyze the energy structure of the spin glass phase space (see for e.g., Phys. Rev. B 100 (9), 09420, 2109). We find a waiting time effect down to at least 5 nanometers and we will report on samples with thinner layer thicknesses.