Using first-principles electronic structure calculations we investigate the existence of stable ferromagnets among the AIV/Fe digital alloys (AIV=Si,Ge), modeled as periodic sequence of Fe monolayers in the AIV host. Total-energy calculations and the magnetic force theorem are exploited for accurate determination of the magnetic ordering. To estimate the critical temperatures, Monte Carlo simulations are employed, while the renormalization-group analytical expressions are applied to assess the impact of the interlayer exchange on the critical temperature values. According to our results, among the systems under consideration only the Ge-based alloys feature a stable ferromagnetic ordering at nonzero temperature. The critical temperatures of these systems were found to be strongly dependent on the underlying crystal structure. © 2012 American Physical Society.

This work was supported by the Sonderforschungsbereich SFB 762, “Functionality of Oxidic Interfaces.” We also acknowledge the support by the University of the Basque Country [Proyecto GV-UPV/EHU (under Grant No. IT-366-07) and Spanish Ministerio de Ciencia y Tecnología (Grant No. FIS2010-19609-C02-01)].

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