Source abstract
Abstract
Using Density Functional Theory (DFT) calculations and Monte-Carlo (MC) simulations, we investigate the recently reported magnetic transition in B2 Al–Cr–Co alloys. The Cr sublattice is alloyed with different amounts of Co in the antiferromagnetic (AFM) B2 AlCr binary alloy and the resulting exchange interactions are analyzed within the Heisenberg Hamiltonian framework. DFT results reveal that at low Co concentrations the system favors the AFM order, while at high Co contents a transition to the ferromagnetic (FM) state is observed. Within the FM stability field, the Curie temperature (TC), obtained within the mean-field approximation, is below ∼160 K and decreases with Co concentration. The calculated exchange parameters evolve systematically with Co content, and the trends are consistent with the DFT total energies. The magnetic configurations obtained from MC simulations follow the DFT results at low Cr levels but predict a spin-glass behavior for alloys containing more than 40 at. % Co on Cr sublattice. These findings provide a fundamental understanding of how the chemistry-driven changes in exchange interactions affect magnetism in the B2 Al–Cr–Co alloys.
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Affiliations
Department of Materials Science and Engineering, KTH Royal Institute of Technology 1 , Stockholm SE-10044,
Wallenberg Initiative Materials Science for Sustainability, Department of Materials Science and Engineering, KTH Royal Institute of Technology 2 , Stockholm,
Faculty of Materials Science and Chemistry, China University of Geosciences 3 , Wuhan 430074,
Department of Physics and Astronomy, Uppsala University 4 , Box 516, SE-75120 Uppsala,
Research Institute for Solid State Physics and Optics, Wigner Research Center for Physics 5 , P.O. Box 49, H-1525 Budapest,