Local moments and magnetic correlations above the Curie temperature in thin films on and embedded in nonmagnetic substrates: Fe/Cu(100), Co/Cu(100), and Fe/W(100)

S. S A Razee, J. B. Staunton, L. Szunyogh, B. L. Györffy

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Abstract

We describe a mean-field theory of magnetic fluctuations in layered metallic materials at finite temperatures. It has a first-principles electronic structure basis and uses the spin-polarized screened Korringa-Kohn-Rostoker method and the coherent-potential approximation to describe the effects of the fluctuating "local moments" upon the electronic structure. At no stage is there a fitting to an effective classical Heisenberg model. From this disordered local moment picture we find the layer dependent paramagnetic spin susceptibility of films and multilayers above the Curie temperature Tc which describes how the type of magnetic correlations varies layer by layer. We study thin films of Fe and Co (1-8 layers) on and embedded in nonmagnetic substrates, specifically bcc-Fe/W(100), fcc-Fe/Cu(100), and fcc-Co/Cu(100). In uncapped Fe/W(100) we find intralayer ferromagnetic correlations in all thicknesses of the iron film except in the layer nearest the W substrate in agreement with experiment. The interlayer couplings are also ferromagnetic and short ranged. There are also ferromagnetic intralayer and interlayer couplings throughout the Co films in fcc-Co/Cu(100). In the Fe/Cu(100) system the top two layers are coupled ferromagnetically and the rest antiferromagnetically. Cu capping has a profound effect upon the magnetic coupling in both Fe/Cu(100) and Co/Cu(100) with Tc showing an oscillating behavior as a function of the cap layer thickness. In contrast there is no dramatic effect when Fe films are embedded in W(100).

Original languageEnglish
Article number094415
Pages (from-to)944151-9441510
Number of pages8497360
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume66
Issue number9
Publication statusPublished - Sep 1 2002

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Curie temperature
moments
Thin films
Substrates
thin films
Electronic structure
Magnetic couplings
Mean field theory
interlayers
Multilayers
electronic structure
Iron
caps
magnetic permeability
Experiments
iron
Temperature
approximation

ASJC Scopus subject areas

  • Condensed Matter Physics

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Local moments and magnetic correlations above the Curie temperature in thin films on and embedded in nonmagnetic substrates : Fe/Cu(100), Co/Cu(100), and Fe/W(100). / Razee, S. S A; Staunton, J. B.; Szunyogh, L.; Györffy, B. L.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 66, No. 9, 094415, 01.09.2002, p. 944151-9441510.

Research output: Contribution to journalArticle

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