Anomalous interface magnetism in ultrathin Co films with in-plane anisotropy

Schumann, F. O.; Buckley, Mary; Bland, J. A. C.

doi:10.1063/1.358381

Cited by 24 publications

(17 citation statements)

References 15 publications

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“…Since that time, the impact of the reduced symmetry at surfaces [2 -4], interfaces [5], and thin films [6] on interfacial magnetic moments has been of major interest. For example, variation in the magnetic anisotropy or exchange coupling is observed as foreign atoms are adsorbed onto clean 3d magnetic surfaces [7][8][9], thereby allowing surface and thin film magnetic properties to be tailored. It is known that such phenomena result from the spin-orbit coupling between orbital and spin moments near the surface [6,10].…”

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confidence: 99%

Spin-Resolved Photoemission of Surface States ofW(110)−(1×1)H

et al. 2002

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The surface electronic states of W(110)-(1 x 1)H have been measured using spin- and angle-resolved photoemission. We directly demonstrate that the surface bands are both split and spin-polarized by the spin-orbit interaction in association with the loss of inversion symmetry near a surface. We observe 100% spin polarization of the surface states, with the spins aligned in the plane of the surface and oriented in a circular fashion relative to the Smacr; symmetry point. In contrast, no measurable polarization of nearby bulk states is observed.

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confidence: 99%

Spin-Resolved Photoemission of Surface States ofW(110)−(1×1)H

et al. 2002

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“…We first observe that M(H) loops in the ͓110͔ direction are not fully square, in contrast to the usual easy magnetization behavior for the Co/ Cu͑001͒ system, where fcc Co has a large in-plane fourfold anisotropy and its easy axes lie along the ͕110͖ crystallographic directions. 4 This indicates that the magnetic easy axis of the fcc Co͑001͒ departs from the fourfold ͓110͔ easy axis. M(H) loops in the ͓100͔ direction for the uncovered Co are also nearly square and fully saturated at 250 Oe.…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3][4] Much attention has been recently given to studies of the structure and magnetism of two-dimensionally ͑2D͒ ordered surface alloys based on transition metals, since they provide important insights into the effects of the adsorbed nonmagnetic atoms on the magnetic ordering in ultrathin magnetic films. 5,6 A wide range of Mn surface alloys, based on Mn/Cu͑001͒, Mn/Ni͑001͒, and Mn/Fe͑001͒, [6][7][8][9] have been studied theoretically and experimentally, both because of a rich variety of possible structural and magnetic phases occurring in epitaxially grown Mn films and because a large magnetic moment can form due to the half-filled 3d shell of Mn.…”

Section: Introductionmentioning

confidence: 99%

Magnetic anisotropy strength and surface alloy formation in Mn/Co/Cu(001) overlayers

1999

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The correlation between the structure and magnetic properties of ultrathin Mn overlayers grown on fcc Co/Cu͑001͒ was studied using low-energy electron diffraction and the magneto-optic Kerr effect in situ. A two-dimensional magnetic c͑2ϫ2͒ Mn-Co͑001͒ surface alloy was found to be stabilized in the range 0.3-0.8 ML Mn overlayer thickness. Within this thickness range Mn is ferromagnetically coupled to the fcc Co͑001͒ underlayer. Above one monolayer of Mn, the c͑2ϫ2͒ surface reconstruction fully disappears and the Mn overlayers are no longer ferromagnetically ordered. Furthermore, it is shown that the Kerr signal, magnetic anisotropy strength, and coercivity are correlated with the stabilization of the MnCo surface alloy and growth conditions. ͓S0163-1829͑99͒02709-5͔

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“…Subsequently, careful structural studies by Kief and Egelhoff 22 showed that surface segregation of Cu occurs at elevated temperatures. Schumann et al later demonstrated that the deposition of submonolayer coverages of nonmagnetic Cu on fcc Co͑001͒ ultrathin films with in-plane anisotropy can cause a reduction in the Co layer coercivity by ϳ300% for appropriate Co layer thicknesses, 23 illustrating how dramatic overlayer induced effects can be. This result can be used to explain the temperature dependence of the coercivity and is believed to arise from the preferential nucleation of Cu at edge sites provided by atomic steps in the Co film.…”

Section: Interface Induced Magnetic Anisotropiesmentioning

confidence: 99%

Magnetic anisotropy engineering in in-plane magnetized ultrathin ferromagnetic films (invited)

Bland¹,

Hope²,

Choi³

et al. 1999

Journal of Applied Physics

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We have studied the effect of depositing submonolayer quantities of Cu onto the CO exposed Co/Cu͑110͒ system at room temperature using the magneto-optic Kerr effect. Cu overlayers are found to completely reverse the in-plane 90°easy axis switch caused by the CO adsorption, for all Co thicknesses studied up to 40 ML. The Cu reverses the sign of the effective in-plane uniaxial anisotropy K U eff thereby switching the easy axis from the ͓1-10͔ to the ͓001͔ direction. Two modes of switching are observed depending on the magnitude of the cubic magnetocrystalline anisotropy constant K 1 which is in turn dependent on the thickness of the Co films. For sufficiently thick Co films (d Co Ͼ15 ML), the easy axis is found to shift gradually from the ͓1-10͔ to the ͓001͔ direction due to the competition between the cubic and effective uniaxial anisotropy contributions. Therefore, we are able to controllably engineer the direction of the easy axis in this system as a function of Cu overlayer thickness. For thin Co films (d Cu Ͻ15 ML) K 1 tends to zero as revealed by BLS measurements of Hillebrands et al. and the easy axis switch is abrupt. We have engineered an experimental realization of an isotropic two-dimensional XY magnet by depositing submonolayer coverages of Cu onto a CO exposed 5 ML Co/Cu͑110͒ film with a zero cubic anisotropy component K 1 at room temperature. For a Cu coverage of 1.02 ML, the uniaxial anisotropy component vanishes also, and we observe a corresponding loss of ferromagnetic order at remanence. Further Cu deposition restores the uniaxial anisotropy and the magnetic order. Therefore we have directly observed the stabilization of ferromagnetic order by magnetic anisotropy in an ultrathin magnetic film, as theoretically predicted.

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Anomalous interface magnetism in ultrathin Co films with in-plane anisotropy

Cited by 24 publications

References 15 publications

Spin-Resolved Photoemission of Surface States ofW(110)−(1×1)H

Spin-Resolved Photoemission of Surface States ofW(110)−(1×1)H

Magnetic anisotropy strength and surface alloy formation in Mn/Co/Cu(001) overlayers

Magnetic anisotropy engineering in in-plane magnetized ultrathin ferromagnetic films (invited)

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