Magnetism in Cr thin films on Fe(100)

Unguris, John; Rj, Celotta; Dt, Pierce

doi:10.1103/physrevlett.69.1125

Cited by 243 publications

(111 citation statements)

References 14 publications

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“…This affords the opportunity to study how the magnetism at the F/AF interface develops with increasing thickness of the AF shell. It has been known for some time that in Cr layers deposited onto flat Fe surfaces, the direction of surface magnetisation oscillates as a function of Cr layer thickness with a period of two monolayers [21] and it is assumed that the magnetisation at the Fe surface is unaffected. Here we study the magnetic behaviour as the Cr layer grows around Fe nanoparticles, which is a highly frustrated system in which different behaviour is expected.…”

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confidence: 99%

Exchange Bias in Fe@Cr Core–Shell Nanoparticles

et al. 2013

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We have used X-Ray Magnetic Circular Dichroism (XMCD) and magnetometry to study isolated Fe@Cr core-shell nanoparticles with an Fe core diameter of 2.7 nm (850 atoms) and a Cr shell thickness varying between 1 and 2 monolayers. The addition of Cr shells significantly reduces the spin moment but does not change the orbital moment. At least two Cr atomic layers are required to stabilize a ferromagnetic/antiferromagnetic interface and generate the associated exchange bias and increase in coercivity.

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confidence: 99%

Exchange Bias in Fe@Cr Core–Shell Nanoparticles

et al. 2013

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“…An odd number of Cr layers is expected to favor ferromagnetic (FM) coupling, but instead of that antiferromagnetic (AFM) spin structures are observed (Unguris, Celotta and Pierce, 1992), due to alloying effects at the interface. In addition, it is known that Cr itself has an incommensurate spin density wave (Fawcett, 1988), but if it is deposited on a surface the magnetic behavior changes, and collinear spin structures are favored.…”

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confidence: 99%

Ab Initio Study of Iron and Cr/Fe(001)

2002

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In the present paper interfacial mixing of a thin chromium overlayer on bcc iron is studied. The calculations are performed in the framework of a pseudo-potential technique using the generalized gradient approximation for the exchange-correlation functional. Although Fe and Cr do not alloy in the bulk system at low temperatures, strong intermixing effects have been observed with Auger spectroscopy, if Cr is epitaxially grown on bcc Fe(001). Besides these structural effects we discuss the magnetic structure of the interface. It can be shown that the results are in good agreement with the experimental findings of Pfandzelter (Pfandzelter, Igel and Winter, 1996), provided we allow for lattice relaxation. Additionally, the structural and magnetic properties of iron investigated by the pseudo-potential method are compared to our former full potential results.

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“…In this context, the role of the Fe/Cr interface is a matter of intense study [5,6]. Magnetic domain imaging of an Fe layer deposited on a wedge shaped Cr layer on an Fe whisker shows a domain pattern switching between parallel and anti-parallel alignments having a periodicity of two Cr(001) monolayers and a phase shift consistent with a SDW state [7]. More recently, neutron scattering and perturbed angular correlation spectrocopy (PACS) have been used on Fe/Cr(001) superlattices to investigate the magnetic structure of Cr directly for Cr film thicknesses t Cr of about 30 -400Å [8][9][10].…”

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Reorientation of Spin Density Waves in Cr(001) Films Induced by Fe(001) Cap Layers

Bödeker

Hucht²,

Schreyer

et al. 1998

Phys. Rev. Lett.

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Proximity effects of 20Å thin Fe layers on the spin density waves (SDWs) in epitaxial Cr(001) films are revealed by neutron scattering. Unlike in bulk Cr we observe a SDW with its wave vector Q pointing along only one {100} direction which depends dramatically on the film thickness tCr. For tCr < 250Å the SDW propagates out-of-plane with the spins in the film plane. For tCr > 1000Å the SDW propagates in the film plane with the spins out-of-plane perpendicular to the in-plane Fe moments. This reorientation transition is explained by frustration effects in the antiferromagnetic interaction between Fe and Cr across the Fe/Cr interface due to steps at the interface.PACS numbers: 75.25.+z, 75.30.Fv While the incommensurate spin density wave (SDW) antiferromagnetism is well established for bulk Cr [1], it is presently of high interest to analyze how the magnetic properties of Cr are altered either by reduced dimensionality in thin films or by proximity effects to ferromagnetic (FM) layers. The magnetic state of Cr is particularly interesting since ultrathin Cr films play an important role in exchange coupled Fe/Cr superlattices exhibiting giant magneto-resistance effects [2,3]. Also for theoretical treatments of the exchange coupling it is uncertain whether the Cr spacer layer should be treated as a paramagnet, an antiferromagnet, or as a proximity induced antiferromagnet [4]. In this context, the role of the Fe/Cr interface is a matter of intense study [5,6]. Magnetic domain imaging of an Fe layer deposited on a wedge shaped Cr layer on an Fe whisker shows a domain pattern switching between parallel and anti-parallel alignments having a periodicity of two Cr(001) monolayers and a phase shift consistent with a SDW state [7]. More recently, neutron scattering and perturbed angular correlation spectrocopy (PACS) have been used on Fe/Cr(001) superlattices to investigate the magnetic structure of Cr directly for Cr film thicknesses t Cr of about 30 -400Å [8][9][10]. Although some inconsistencies still remain, these experiments show that the SDW state collapses for Cr films well below the period Λ of the SDW.The aim of the present work is to gain a basic understanding of the effect of FM proximity layers on the magnetic properties of thin Cr(001) films in the SDW phase. The thickness range of the Cr films (200 -3000 A) is chosen such that the question of the presence of a SDW state is not an issue. Using neutron scattering we find that the propagation direction of the SDW depends dramatically on the Cr film thickness. Our experimental results are rationalized by computer simulations using a Heisenberg model which takes realistic Fe/Cr interfaces with interfacial roughness and interdiffusion into account. Complementary experiments with synchrotron radiation will be discussed elsewhere.We have grown epitaxial Fe/Cr(001) bilayers by molecular beam epitaxy on Al 2 O 3 (1102) substrates with a 500Å thick Nb(001) buffer layer, following well established growth recipies [11,12]. Cr(001) films with thicknesses from 200 -3000Å ...

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Magnetism in Cr thin films on Fe(100)

Cited by 243 publications

References 14 publications

Exchange Bias in Fe@Cr Core–Shell Nanoparticles

Exchange Bias in Fe@Cr Core–Shell Nanoparticles

Ab Initio Study of Iron and Cr/Fe(001)

Reorientation of Spin Density Waves in Cr(001) Films Induced by Fe(001) Cap Layers

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