Electrical spin injection from ferromagnetic MnAs metal layers into GaAs

Ramsteiner, M.; Hao, Hsin‐Yi; Kawaharazuka, Atsushi; Zhu, Haoxiang; Kästner, M.; Hey, R.; Däweritz, L.; Grahn, H. T.

doi:10.1103/physrevb.66.081304

Cited by 192 publications

(99 citation statements)

References 21 publications

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“…13 The excellent quality of MnAs/GaAs heterostructures makes this compound particularly interesting for hybrid metal/semiconductor spintronics. 14,15,16,17 The epitaxy introduces strain and defects in MnAs thin films that significatively modify their structural and magnetic properties with repect to the bulk. When MnAs is grown on GaAs(100) or GaAs(111)B, epitaxial strain induces an α/β-phases coexistence in a wide range of temperature.…”

Section: Introductionmentioning

confidence: 99%

Magnetization reversal and anomalous dependence of the coercive field with temperature in MnAs epilayers grown on GaAs

et al. 2006

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The magnetic properties of MnAs epilayers have been investigated for two different substrate orientations: GaAs(100) and GaAs(111). We have analyzed the magnetization reversal under magnetic field at low temperatures, determining the anisotropy of the films. The results, based on the shape of the magnetization loops, suggest a domain movement mechanism for both types of samples. The temperature dependence of the coercivity of the films has been also examined, displaying a generic anomalous reentrant behavior at T>200 K. This feature is independent of the substrate orientation and films thickness and may be associated to the appearance of new pinning centers due to the nucleation of the β-phase at high temperatures.

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Section: Introductionmentioning

confidence: 99%

Magnetization reversal and anomalous dependence of the coercive field with temperature in MnAs epilayers grown on GaAs

et al. 2006

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“…5 In recent theoretical calculations, in addition, it has been predicted that the electronic band-structure of hypothetical zinc-blende ͑ZB͒-type MnAs layers is half-metallic, which is promising nature for device applications.…”

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Magnetic domain characterizations of anisotropic-shaped MnAs nanoclusters position-controlled by selective-area metal-organic vapor phase epitaxy

Ito

Hara

Wakatsuki

et al. 2009

Applied Physics Letters

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The authors report the buildup fabrication and magnetic domain characterizations of anisotropic-shaped MnAs nanoclusters position-controlled on partially SiO 2 -masked GaAs ͑111͒B substrates by selective-area metal-organic vapor phase epitaxy. Magnetic force microscopy reveals that both the symmetric-and anisotropic-shaped nanoclusters show spontaneous magnetization at room temperature. Some of the nanoclusters show a single magnetic domain, in which magnetized directions are along one of the a-axes of NiAs-type MnAs, after the external magnetic fields up to 3500 Gauss are applied in-plane. The magnetic domains are well controlled by introducing both magnetocrystalline and shape magnetic anisotropies in the anisotropic-shaped nanoclusters. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3157275͔ Recent research activities for heteroepitaxial nanostructures of ferromagnet and III-V compound semiconductor ͑FM III-V hybrids͒ have gained much attention in the future nanospintronic device applications.1 It was reported that large tunneling magnetoresistance effect was shown in the MnAs/AlAs/MnAs heterostructures 2 and the GaAs:MnAs granular layers 3,4 above room temperature ͑RT͒, and that ferromagnetic NiAs-type MnAs layers served as an electrical spin injection source for semiconductors. 5 In recent theoretical calculations, in addition, it has been predicted that the electronic band-structure of hypothetical zinc-blende ͑ZB͒-type MnAs layers is half-metallic, which is promising nature for device applications.6-8 Thus far, conventional approaches to realizing nanospintronic devices using FM III-V hybrids have been mostly "top-down" fabrication techniques after the epitaxy because it has been necessary to grow the epitaxial ferromagnetic and semiconducting layers by molecular beam epitaxy at an extremely low growth temperature. [2][3][4][5]9

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“…11 Ferromagnetic MnAs thin films, in addition, serve as an electrical spin injection source into semiconductors. 12 For the growth of hexagonal NiAs-type MnAs layers, ͕111͖ orientations of zinc-blende ͑ZB͒-type materials are promising because of the similarity of the crystallographic structures. MnAs "thin films" have been grown not only on GaAs ͑111͒B ͑Refs.…”

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confidence: 99%

Hexagonal ferromagnetic MnAs nanocluster formation on GaInAs∕InP (111)B layers by metal-organic vapor phase epitaxy

Hara

Fukui

2006

Applied Physics Letters

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The authors report the self-assembly of hexagonal MnAs nanoclusters on GaInAs ͑111͒B surfaces by metal-organic vapor phase epitaxy. The ferromagnetic behavior of the nanoclusters dominates the magnetic response of the samples when magnetic fields are applied in a direction parallel to the wafer plane. For the magnetic fields applied in a direction perpendicular to the plane, diamagnetic characteristics are dominant. The results indicate that the c axis of the nanoclusters is perpendicular to the plane, and that their a axis is in plane. They are consistent with the results of crystallographic analysis, where the nanoclusters' c axis is shown to be along a GaInAs ͓−1−1−1͔ direction. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2349309͔Ferromagnetic materials hybridized in III-V compound semiconductors ͑FM III-V hybrids͒ and III-V compoundbased diluted magnetic semiconductors ͑III-V DMSs͒ are promising for the realization of nanospintronic devices using not only the charge but the spin of carriers. In MnAs/ GaAs, GaMnAs, and InMnAs materials systems where extensive research efforts have been carried out, magnetic thin films have been grown on GaAs layers by molecular beam epitaxy at an extremely low growth temperature ͑LT-MBE͒, 1-3 implantation of magnetic ions into semiconductors, 4 and metalorganic vapor phase epitaxy ͑MOVPE͒. 5,6 We have pursued FM III-V hybrids, in particular, using MnAs nanoclusters ͑NCs͒ embedded in GaInAs/ InP ͑001͒ layers grown by MOVPE. 7,8 InP-related materials are more suitable for the fabrication of key devices in optical communication systems for 1.3 and 1.55 m wavelength bands. Recently, LT-MBE of III-V DMS, e.g., GaInMnAs, on InP ͑001͒ wafers has been reported, 9,10 and waveguide-type optical isolators using the magneto-optical effects of MnAs NCs have been proposed. 11 Ferromagnetic MnAs thin films, in addition, serve as an electrical spin injection source into semiconductors. 12 For the growth of hexagonal NiAs-type MnAs layers, ͕111͖ orientations of zinc-blende ͑ZB͒-type materials are promising because of the similarity of the crystallographic structures. MnAs "thin films" have been grown not only on GaAs ͑111͒B ͑Refs. 13-18͒ but on Si ͑111͒ ͑Ref. 19͒ surfaces by LT-MBE. Another potential advantage using the ͕111͖ orientations is the catalyst-free formation of onedimensional ͑1D͒ semiconductor nanowires ͑NWs͒ using selective-area MOVPE as promising building blocks for future nanophotonics and electronics. 20,21 The hybridization of ferromagnetic NCs into 1D semiconductor NWs possibly leads to the understanding of physical properties in 1D spinpolarized electronic systems and the realization of 1D nanospintronic devices in the next generation. We believe that the MOVPE techniques in the present work are one of the most powerful methods to meet this future goal. In this letter, we demonstrate the self-assembly of ferromagnetic MnAs NCs on planar GaInAs ͑111͒B surfaces by MOVPE. This letter describes the results of fundamental crystallographic and magnetic characterizations...

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Electrical spin injection from ferromagnetic MnAs metal layers into GaAs

Cited by 192 publications

References 21 publications

Magnetization reversal and anomalous dependence of the coercive field with temperature in MnAs epilayers grown on GaAs

Magnetization reversal and anomalous dependence of the coercive field with temperature in MnAs epilayers grown on GaAs

Magnetic domain characterizations of anisotropic-shaped MnAs nanoclusters position-controlled by selective-area metal-organic vapor phase epitaxy

Hexagonal ferromagnetic MnAs nanocluster formation on GaInAs∕InP (111)B layers by metal-organic vapor phase epitaxy

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