Molecular-beam-epitaxy growth and structural characterization of high-quality single-crystal Co/Cr(001) superlattices

Donner, W.; Metoki, Naoto; Abromeit, A.; Zabel, H.

doi:10.1103/physrevb.48.14745

Cited by 31 publications

(7 citation statements)

References 22 publications

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“…4. The structural results completely agree with the earlier measurements reported by Metoki et al 21 and Donner et al, 22,23 and in particular, confirm the martensitic phase bcc-hcp structural phase transition as a function of Co thickness.…”

Section: Structural Characterizationsupporting

confidence: 82%

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Direct observation of Cr spin polarization in epitaxial Cr/Co/Cr(100) trilayers

et al. 2013

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The spin polarization of chromium at the interface next to a ferromagnetic layer is of general interest because of the competing ferromagnetic and antiferromagnetic exchange coupling. While the Fe/Cr interface has been well studied, information on the Co/Cr interface still remains scarce. Here we show for epitaxially grown Cr/Co/Cr(100) trilayers with smooth interfaces x-ray resonant magnetic scattering (XRMS) results in a saturation field of ±270 mT, recorded at the Co and Cr L 3 edges, respectively. The XRMS results at the Co edge show the expected asymmetry and a ferromagnetic hysteresis for different incident angles θ. Furthermore, XRMS measurements with the energy tuned to the Cr L 3 edge also exhibit an asymmetry, albeit much smaller than the one at the Co L 3 edge. Moreover, the magnetic hysteresis of Cr taken at the L 3 edge has a sign opposite to that of Co at the L 3 edge over a broad range of incident angles. From these results we infer first that at the Co/Cr interface chromium is ferromagnetically polarized, and second that its spin structure is oriented opposite to the magnetization of Co.

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Section: Structural Characterizationsupporting

confidence: 82%

“…The growth properties are detailed in Ref. 21 22 In addition to this a bcc-hcp martensitic transition takes place as a function of Co thickness within a thickness range up to 4.0 nm. [21][22][23] The top Cr layer thickness is chosen such that it protects the sample from oxidation.…”

Section: Sample Design and Growth Parametersmentioning

confidence: 99%

Direct observation of Cr spin polarization in epitaxial Cr/Co/Cr(100) trilayers

et al. 2013

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“…3, exhibits eight well-defined peaks with a pair of peaks separated by 45°a ccompanying each V͑020͒ reflection. The origin of this pseudocubic in-plane symmetry of the Co-layer is known to result from two types of crystalline domains formed during the epitaxial growth of hcp Co on bcc V. 36,39 …”

Section: A Structural Propertiesmentioning

confidence: 99%

Superconducting spin valves based on epitaxial Fe/V superlattices

et al. 2008

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In superconducting spin valves of the type S/F1/N/F2 or F1/S/F2 with a superconducting layer S, two ferromagnetic layers F1 and F2, and a normal metallic layer N, the superconducting transition temperature T S depends on the relative magnetization direction of the ferromagnetic layers F1 and F2. The difference of the transition temperature ⌬T S = T s AP − T s P with the magnetization direction of F1 and F2 either antiparallel or parallel is called the superconducting spin valve effect. We have prepared both types of spin valves by growing Fe/V thin-film heterostructures with epitaxial quality on MgO͑001͒ substrates. In the S/F1/N/F2-type spin valves the ferromagnetic layers were the first two Fe layers of a ͓Fe/V͔ superlattice coupled antiferromagnetically via the interlayer exchange interaction. Here we observed a superconducting spin valve shift of up to ⌬T S Ϸ 200 mK when aligning the sublattice magnetization in an external magnetic field. In the F1/S/F2-type spin valves the ferromagnetic layer F1 was either a ͓Fe/V͔ or a ͓Fe x V 1−x / V͔ superlattice, the F2 layer was a Fe-, a Co-, or a Fe x V 1−x film. Using weakly ferromagnetic Fe x V 1−x alloy layers as F1 and F2 we find a spin valve effect of up to ⌬T S Ϸ 20 mK, which is more than a factor of 2 larger than reported in the literature before for spin valves with comparable transition temperatures. Our results indicate that a high interface transparency and a large superconducting correlation length are prerequisites for the observation of a sizable superconducting spin valve effect.

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“…However, because of similarities between the hcp(1 12 0) and the bcc(0 0 1) surfaces and small lattice mismatches of 0.07% parallel to Co[0 0 0 1] but 6.4% along Co[1 12 0], Co grows pseudomorphically on Cr(0 0 1) by adopting its bcc structure. Subsequently, Co undergoes a continuous bcc-hcp phase transition during growth over a thickness range of 4-5 nm [10]. Because of two equivalent {1 1 0} in-plane axes in Cr(0 0 1) two different Co(1 12 0) domains form with an angle of 90 • to each other.…”

Section: Sample Preparationmentioning

confidence: 99%

“…The epitaxy of Fe on the Cr buffer is pseudomorphic because of a lattice mismatch of only 0.6% between both bcc materials. In contrast, Co is a hcp material and grows in (1 12 0) orientation on Cr(0 0 1) with Co[0 0 0 1] being parallel to Cr[1 1 0] [10,11]. However, because of similarities between the hcp(1 12 0) and the bcc(0 0 1) surfaces and small lattice mismatches of 0.07% parallel to Co[0 0 0 1] but 6.4% along Co[1 12 0], Co grows pseudomorphically on Cr(0 0 1) by adopting its bcc structure.…”

Section: Sample Preparationmentioning

confidence: 99%

Magnetization reversal and magnetic interactions in patterned spin valve structures

Brüssing¹,

Nowak²,

Schumann³

et al. 2009

J. Phys. D: Appl. Phys.

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We have investigated the magnetization reversal and the magnetic anisotropy of epitaxial Co(1 12 0) and Fe(0 0 1) films and compared them with epitaxial Co(1 12 0)/Cr(0 0 1)/Fe(0 0 1) trilayers with spin valve characteristics. Furthermore, by e-beam lithography we have cut the single layers and the trilayers into the shape of wires to study the effect of the shape anisotropy and the dipolar interaction between the wires on their switching characteristics. We found that patterning very much affects the magnetization reversal of the single films by introducing an additional anisotropy term. Dipolar interaction between the different wires may exist but is less obvious. However, the remagnetization process of the patterned trilayers resembles more those of the continuous single films than a combination of the Co and Fe wires. We argue that this is due to a weak but remaining interlayer exchange coupling between Co and Fe, mediated by the intervening Cr layer.

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Molecular-beam-epitaxy growth and structural characterization of high-quality single-crystal Co/Cr(001) superlattices

Cited by 31 publications

References 22 publications

Direct observation of Cr spin polarization in epitaxial Cr/Co/Cr(100) trilayers

Direct observation of Cr spin polarization in epitaxial Cr/Co/Cr(100) trilayers

Superconducting spin valves based on epitaxial Fe/V superlattices

Magnetization reversal and magnetic interactions in patterned spin valve structures

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