Magnetization studies of type-II antiferromagnetic EuTe/PbTe superlattices

Molecular-beam-epitaxy grown EuTe(ξ )/PbTe(η ) short-period superlattices (SL’s) with ξ=3, 4, 5 magnetic EuTe (111) monolayers alternating with η nonmagnetic PbTe monolayers, such that η = 3ξ, were studied by superconducting quantum interference device magnetometry. The SL chemical structure was investigated by high resolution x-ray diffraction measurements, and the results show that both EuTe and PbTe grow epitaxially in the fcc structure. The magnetic study focuses on the temperature-dependent magnetization M(T) for SL’s. Specifically, we find the M(T) profiles for SL to be very different from that of bulk EuTe. Further, among the three SL samples of the present study, the M(T) for ξ = 4 SL’s is antiferromagneticlike, whereas, M(T) for ξ = 3 and 5 SL’s is ferromagneticlike. Each SL sample shows a distinct magnetic phase transition, and the magnetic transition temperature ${\mathit{T}}_{\mathit{c}}$ increases monotonically as ξ increases. The transition temperatures (${\mathit{T}}_{\mathit{c}}$) for SL’s were calculated using an iterative mean-field method, and the functional forms of M(T) for SL’s were analyzed based on a mean-field approach. © 1996 The American Physical Society.