Magnetization of thin Gd films on W(110) near the Curie temperature

Farle, Michael; Lewis, W. A.

doi:10.1063/1.355655

Cited by 41 publications

(13 citation statements)

References 16 publications

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“…[1][2][3][4][5][6][7][8][9][10][11][12] This system of a 4 f ferromagnetic metal deposited on a nonmagnetic transition metal has provided much interesting data, including, for example, indications of an elevated surface Curie temperature. 1,2 Although particular growth modes and film morphologies for this system have been inferred indirectly from techniques such as Auger electron spectroscopy ͑AES͒ and low-energy electron diffraction ͑LEED͒, 1,13 no direct observations of surface morphology using scanning-tunneling microscopy ͑STM͒ have been made.…”

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confidence: 98%

Relationship between morphology and magnetic behavior for Gd thin films on W(110)

Westphal

et al. 1996

Phys. Rev. B

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We have used scanning-tunneling microscopy to study the structure of Gd thin films grown on W͑110͒ and its relationship to the magnetic properties. The film morphology is examined for different coverages and for two different post-deposition annealing temperatures ͑530 and 710 K͒, permitting predictions of the in-plane demagnetization factor and the Curie temperature that are in excellent agreement with prior ac magneticsusceptibility measurements. The first monolayer of Gd is also found to grow in a (7ϫ14) lateral superstructure, giving rise to in-plane lattice distortions of ϳ1% as compared to the values of bulk Gd.Over the last ten years, a number of studies of the magnetic properties of thin films of Gd grown epitaxially on W͑110͒ single-crystal substrates has been performed. [1][2][3][4][5][6][7][8][9][10][11][12] This system of a 4 f ferromagnetic metal deposited on a nonmagnetic transition metal has provided much interesting data, including, for example, indications of an elevated surface Curie temperature. 1,2 Although particular growth modes and film morphologies for this system have been inferred indirectly from techniques such as Auger electron spectroscopy ͑AES͒ and low-energy electron diffraction ͑LEED͒, 1,13 no direct observations of surface morphology using scanning-tunneling microscopy ͑STM͒ have been made. In this paper, we study the effects of coverage and annealing temperature on the morphology of such Gd films with STM. These results yield a more quantitative understanding of the structure-magnetism relationships for this prototypical epitaxial ferromagnet and also reveal a new superstructure for the first monolayer.Some important prior observations for Gd/W͑110͒ are as follows. Weller et al. 1 proposed based upon AES measurements that Gd films deposited on W͑110͒ substrates held at between 723 and 773 K grow via the Stranski-Krastanov ͑SK͒ mode ͓three-dimensional ͑3D͒ island growth on top of one or more epitaxial monolayers͔. This same work used spin-polarized LEED and the magneto-optic Kerr effect ͑MOKE͒ to determine that the surface Curie temperature (T Cs ) was higher than that of the bulk (T Cb ) by 22 K. A later study by Tang et al. 2 employed spin-polarized secondary electron emission spectroscopy and spin-polarized photoelectron spectroscopy and concluded that T Cs was 60 K higher than T Cb , that there was a ferromagnetic alignment of the in-plane component of the surface and bulk moments, and that the surface magnetization appeared to be canted. Gd is thus one of only two ferromagnetic materials for which T Cs has been observed to be greater than T Cb , with the other being Tb͑001͒, as studied by Rau et al. using electron capture by deuterons 14 Kolaczkiewicz et al. 13 further investigated the growth modes and surface structures of Gd/W͑110͒ utilizing LEED and AES. From breaks in AES intensities as a function of coverage, ⌰, they inferred that, for lower coverages ͓⌰Ͻ3 monolayers ͑ML͔͒ and when deposited at room temperature, Gd grows in the Frank-Van der Merwe ͑FM͒ mode ͑smooth, lay...

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Relationship between morphology and magnetic behavior for Gd thin films on W(110)

Westphal

et al. 1996

Phys. Rev. B

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“…The broadening is attributed to the distribution of local environments created by disorder. T C cannot be determined accurately from the minimum of dM͑T͒ / dT, and instead is found by fitting M͑T͒ to a distribution of Curie temperatures: [20][21][22] …”

Section: A the Paramagnetic Regimementioning

confidence: 99%

Disorder-induced depression of the Curie temperature in mechanically milledGdAl2

et al. 2004

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Shand, P.M.; Stark, C.; Pekarek, T.M.; Yue, Lanping; Petkov, V.; and Leslie-Pelecky, Diandra, "Disorder-induced depression of the Curie temperature in mechanically milled GdAl 2 " (2004 The effect of disorder on the ferromagnetic transition is investigated in mechanically milled GdAl 2 . GdAl 2 is a ferromagnet when crystalline and a spin glass when amorphous. Mechanical milling progressively disorders the alloy, allowing observation of the change from ferromagnetic to a disordered magnetic state. X-ray diffraction and pair-distribution-function analysis are used to determine the grain size, lattice parameter, and mean-squared atomic displacements. The magnetization as a function of temperature is described by a Gaussian distribution of Curie temperatures. The mean Curie temperature decreases with decreasing lattice parameter, where lattice parameter serves as a measure of defect concentration. Two different rates of change with lattice parameter are observed: the first, slower rate occurs while grain size is changing, and the grain size is constant in the second regime. The breadth of the Curie temperature distribution is linear with lattice parameter. Milled and annealed GdAl 2 shows that the mean Curie temperature has the same general dependence on lattice parameter as milled, but unannealed GdAl 2 , while the breadth of the Curie temperature distribution is different in annealed samples compared to the unannealed materials.

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“…These Rare Earth (RE) elements possess low Curie temperatures and so they present a further and particular challenge for many applications. Notwithstanding this the REs have been extensively studied over the last two decades by examining the effect of multilayers (Dy/Er 6 and LuY/Dy 7 ), and for example Gd/W systems with regard to increasing the Curie temperature and enhanced remnant magnetisation 8 . At the same time there is the observation of an improved interfacial coupling in Gd/Fe multilayers 9 but with the recognition of antiferromagnetic (AF) coupling reducing the overall magnetic moment, as is the case in Gd/Y multilayers 10 .…”

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Realizing a high magnetic moment in Gd/Cr/FeCo: The role of the rare earth

Ward

Scheunert

Hendren

et al. 2013

Applied Physics Letters

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The search for materials or systems exhibiting a high magnetic saturation has been of longstanding importance. It has been suggested that increased saturation could be achieved by coupling a transition metal via a spacer to a rare earth. We report Gd/Cr/Fe 70 Co 30 multilayer stacks and find reduced yet modulating magnetic moment as a function of Cr thickness. Through a micro structural analysis the lowered moment is indicated by the nucleation of the ultrathin Gd films into an fcc phase. We discuss the possible solution in terms of quasi-perfect lattice match seed material to promote growth of hcp Gd.Corresponding authors: * cward19@qub.ac.uk # r.m.bowman@qub.ac.uk

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Magnetization of thin Gd films on W(110) near the Curie temperature

Cited by 41 publications

References 16 publications

Relationship between morphology and magnetic behavior for Gd thin films on W(110)

Relationship between morphology and magnetic behavior for Gd thin films on W(110)

Disorder-induced depression of the Curie temperature in mechanically milledGdAl2

Realizing a high magnetic moment in Gd/Cr/FeCo: The role of the rare earth

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