Atomic scale morphology of self-organized periodic elastic domains in epitaxial ferromagnetic MnAs films

Kästner, M.; Herrmann, C.; Däweritz, L.; Ploog, K.

doi:10.1063/1.1512692

Cited by 57 publications

(60 citation statements)

References 12 publications

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“…First of all, the strong thickness dependence of the stripe period observed previously 8 with AFM is confirmed and extended to lower thickness, with average periods of 0.1, 0.2 and 0.8 µm in the 20, 50 and 180 nm thick films, respectively. Although the thin films (thickness 20, 40 and 50 nm) studied have a simple magnetic domain structure, that of the 180 nm thick films was much more complicated.…”

Section: Resultssupporting

confidence: 71%

Nanomagnetism studies with spin‐polarized low‐energy electron microscopy and x‐ray magnetic circular dichroism photoemission electron microscopy

Zdyb

Locatelli

Heun

et al. 2005

Surface & Interface Analysis

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The spin reorientation transition (SRT) of ultrathin Fe-Co alloy films on an Au(111) surface and the magnetic/structural phase transition of epitaxial MnAs films on a GaAs(100) surface are studied by two electron microscopic techniques with very high surface sensitivity, i.e. spin-polarized lowenergy electron microscopy (SPLEEM) and x-ray magnetic circular dichroism photoemission electron microscopy (XMCDPEEM), combined with low-energy electron microscopy (LEEM) and low-energy electron diffraction (LEED), respectively. A new SRT mechanism is found and the interrelation between ferromagnetism and structure is elucidated.

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Section: Resultssupporting

confidence: 71%

Nanomagnetism studies with spin‐polarized low‐energy electron microscopy and x‐ray magnetic circular dichroism photoemission electron microscopy

Zdyb

Locatelli

Heun

et al. 2005

Surface & Interface Analysis

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“…Those films present a nonabrupt phase transition with the coexistence [7] of the two phases in form of periodically alternating stripes [8,9] for a large temperature range (20 C) [7][8][9][10]. As a result of this phase coexistence a considerable fraction of the volume of the MnAs epitaxial films is usually in the paramagnetic phase at 30 C, which is a strong limitation for room temperature spintronic devices.…”

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confidence: 99%

Lattice Distortion Effects on the Magnetostructural Phase Transition of MnAs

et al. 2005

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We present a systematic experimental and theoretical study of the first-order phase transition of epitaxially grown MnAs thin films under biaxial tensile stress. Our results give direct information on the dependence of the phase-transition temperature of MnAs films on the lattice parameters. We demonstrate that an increase of the lattice constant in the hexagonal plane raises the phase-transition temperature (T p ), while an increase of the perpendicular lattice constant lowers T p . The results of calculations based on density functional theory are in good agreement with the experimental ones. Our findings open exciting prospects for magneto-mechanical devices, where the critical temperature for ferromagnetism can be engineered by external stress. DOI: 10.1103/PhysRevLett.95.077203 PACS numbers: 75.70.Ak, 61.50.Ks, 68.60.2p MnAs presents a first-order phase transition at 40 C, changing from ferromagnetic/hexagonal ( -phase NiAs structure) to paramagnetic/orthorhombic ( -phase MnP structure) [1]. This magneto-structural phase transition has important implications for technological applications. The magneto-elastic effects are useful for transducers [2], while their magneto-caloric properties are interesting for developing refrigeration devices [3]. In recent years, the attention given to MnAs has been strongly amplified by the possibility of epitaxial growth on GaAs substrates [4]. The integration of ferromagnetic materials with semiconductors is a subject of great interest for spintronics, and MnAs grown on GaAs is a strong candidate for spin injection devices [5].From the theoretical point of view, the treatment of the first-order phase transition of materials with magnetoelastic properties is a rather complex issue. Early simple phenomenological thermodynamic treatments based on the localized Heisenberg model [1] have been used to explain the properties of MnAs under an external hydrostatic pressure and magnetic field. Sophisticated band structure calculations are required for a precise quantitative analysis, although in this case it is difficult to introduce a statistical treatment to describe a first-order phase transition [6].We present an experimental and theoretical investigation of the magneto-structural phase transition of MnAs films grown on GaAs. Those films present a nonabrupt phase transition with the coexistence [7] of the two phases in form of periodically alternating stripes [8,9] for a large temperature range ( 20 C) [7][8][9][10]. As a result of this phase coexistence a considerable fraction of the volume of the MnAs epitaxial films is usually in the paramagnetic phase at 30 C, which is a strong limitation for room temperature spintronic devices. The growth of MnAs films on different crystal orientations has been suggested as an alternative that can provide higher phase-transition temperatures [10]. The detailed mechanism that associates the crystal distortion (lattice parameter variation) with the phase-transition temperature is, however, still unclear, This issue was addressed in the ear...

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“…For anisotropically strained systems, a stripe pattern is found [8], whereas the isotropically strained system exhibits an island structure with three-fold symmetry. In general, a higher phase transition temperature and a wider phase coexistence temperature range is found for the isotropically strained system [9].…”

Section: Gamentioning

confidence: 94%

Micromagnetic properties of epitaxial MnAs films on GaAs surfaces

Hesjedal¹,

Engel‐Herbert²,

Schaadt³

2007

Phys. Status Solidi (c)

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We present a systematic study of the micromagnetic properties of MnAs deposited by molecular-beam epitaxy on GaAs(001) and GaAs(111)B surfaces. In epitaxial MnAs films, the strain state in MnAs-onGaAs(001) (anisotropic) and MnAs-on-GaAs(111)B (isotropic) has a strong influence on the magnetostructural phase transition and thus the micromagnetic properties. The ferromagnetic α and the β phase coexist over a wide temperature range exhibiting self-organized, magnetically coupled nanostructures. Independent of the substrate orientation, magnetic flux-closure domain patterns are formed in the basal plane of MnAs. The spatial distribution of the phases in equilibrium (stripes and quasi-hexagonal islands, respectively) stabilizes various magnetic states, which were found experimentally and confirmed by micromagnetic simulations.

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Atomic scale morphology of self-organized periodic elastic domains in epitaxial ferromagnetic MnAs films

Cited by 57 publications

References 12 publications

Nanomagnetism studies with spin‐polarized low‐energy electron microscopy and x‐ray magnetic circular dichroism photoemission electron microscopy

Nanomagnetism studies with spin‐polarized low‐energy electron microscopy and x‐ray magnetic circular dichroism photoemission electron microscopy

Lattice Distortion Effects on the Magnetostructural Phase Transition of MnAs

Micromagnetic properties of epitaxial MnAs films on GaAs surfaces

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