First-principles study of thermodynamical properties of random magnetic overlayers on fcc-Cu(001) substrate

0422581 - FZÚ 2014 RIV US eng J - Článek v odborném periodiku
Mašín, Martin - Bergqvist, L. - Kudrnovský, Josef - Kotrla, Miroslav - Drchal, Václav
First-principles study of thermodynamical properties of random magnetic overlayers on fcc-Cu(001) substrate.
Physical Review. B. Roč. 87, č. 7 (2013), "075452-1"-"075452-7". ISSN 1098-0121
Grant CEP: GA ČR GA202/09/0775
Institucionální podpora: RVO:68378271
Klíčová slova: Curie temperature * random overlayer * Heisenberg Hamiltonian * first principles * Monte Carlo simulations * magnon spectra
Kód oboru RIV: BE - Teoretická fyzika
Impakt faktor: 3.664, rok: 2013
http://prb.aps.org/abstract/PRB/v87/i7/e075452

We present a theoretical study of the thermodynamical properties of a fcc-Cu(001) substrate covered by an iron-cobalt monolayer as well as by an incomplete iron layer. The effective two-dimensional Heisenberg Hamiltonian is constructed from first principles and the properties of exchange interactions are investigated. The Curie temperatures are estimated using the Monte Carlo (MC) simulations and compared with a simplified approach using the random-phase approximation (RPA) in connection with the virtual-crystal approach (VCA) to treat randomness in exchange integrals. Calculations indicate a weak maximum of the Curie temperature as a function of composition of the iron-cobalt overlayer. While a good quantitative agreement between RPA-VCA and MC was found for the iron-cobalt monolayer, the RPA-VCA approach fails for low coverage due to the magnetic percolation effect. We also present a study of the effect of alloy disorder on the shape of magnon spectra of random overlayers.
Trvalý link: http://hdl.handle.net/11104/0228718