Spintronics: recent progress and tomorrow's challenges

Tanaka, Masaaki

doi:10.1016/j.jcrysgro.2004.12.078

Cited by 49 publications

(25 citation statements)

References 93 publications

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“…200 This constitutes the subject of special spin-selective type of electronics (spintronics). [201][202][203][204] The giant magnetoresistance (GMR) phenomenon was the first example of the utilization of the electron spin in nanostructured electronic devices as an additional ''degree of freedom''. 205,206 Another effect used in spintronics is tunneling magnetoresistance (TMR).…”

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Magnetic nanoparticles: recent advances in synthesis, self-assembly and applications

et al. 2011

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Nanostructured magnetic materials have a variety of promising applications spreading from nano-scale electronic devices, sensors and high-density data storage media to controlled drug delivery and cancer diagnostics/treatment systems. Magnetic nanoparticles offer the most natural and elegant way for fabrication of such (multi-) functional materials. In this review, we briefly summarize the recent progress in the synthesis of magnetic nanoparticles (which now can be done with precise control over the size and surface chemistry), and nanoscale interactions leading to their self-assembly into 1D, 2D or 3D aggregates. Various approaches to self-organization, directed-, or template-assisted assembly of these nanostructures are discussed with the special emphasis on magnetic-field enabled interactions. We also discuss new physical phenomena associated with magnetic coupling between nanoparticles and their interaction with a substrate and the characterization of the physical properties at the nanoscale using various experimental techniques (including scanning quantum interferometry (SQUID) and magnetic force microscopy). Applications of magnetic nanoparticle assemblies in data storage, spintronics, drug delivery, cancer therapy, and prospective applications such as adaptive materials and multifunctional reconfigurable materials are also highlighted.

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Magnetic nanoparticles: recent advances in synthesis, self-assembly and applications

et al. 2011

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“…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.…”

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confidence: 99%

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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“…The development of a novel class of materials combining standard semiconductors with magnetic elements has recently been driven by considerable technological as well as fundamental scientific interest. While the possibility of a seamless combination of magnetic and semiconducting systems using spins as an additional degree of freedom opens stimulating perspectives in the field of electronics [1,2], reports on materials displaying both semiconducting and ferromagnetic properties have induced great theoretical and experimental efforts in the understanding of the underlying physics [3]. Ga(Mn)As today represents one of the best understood ferromagnets.…”

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Clustering in a Precipitate-Free GeMn Magnetic Semiconductor

et al. 2006

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We present the first study relating structural parameters of precipitate-free Ge 0:95 Mn 0:05 films to magnetization data. Nanometer-sized clusters -areas with increased Mn content on substitutional lattice sites compared to the host matrix -are detected in transmission electron microscopy analysis. The films show no overall spontaneous magnetization at all down to 2 K. The TEM and magnetization results are interpreted in terms of an assembly of superparamagnetic moments developing in the dense distribution of clusters. Each cluster individually turns ferromagnetic below an ordering temperature which depends on its volume and Mn content. DOI: 10.1103/PhysRevLett.97.237202 PACS numbers: 75.50.Pp, 68.37.Lp, 75.75.+a, 81.15.Hi The development of a novel class of materials combining standard semiconductors with magnetic elements has recently been driven by considerable technological as well as fundamental scientific interest. While the possibility of a seamless combination of magnetic and semiconducting systems using spins as an additional degree of freedom opens stimulating perspectives in the field of electronics [1,2], reports on materials displaying both semiconducting and ferromagnetic properties have induced great theoretical and experimental efforts in the understanding of the underlying physics [3]. Ga(Mn)As today represents one of the best understood ferromagnets. This material is one example of a diluted magnetic semiconductor (DMS), meaning a dispersion of the magnetic elements without affecting the semiconducting properties of the matrix [4]. The realization of DMS with maximized ferromagnetic ordering temperatures T C represents the ultimate objective in this field.Special attention has been given to technologically important group IV semiconductor based magnetic materials, with a prominent position for GeMn. Since the first claim of the realization of a Ge based DMS [5], most publications [5][6][7][8] have concentrated on reporting high T C ranging from 116 [5] to 285 K [6] and on interpreting the observed ferromagnetism in terms of DMS theories [9]. It is only recently that several of the former GeMn reports have been questioned by structural proofs [10] and hints [11] for the formation of intermetallic ferromagnetic compounds through phase separation in single crystals and lowtemperature molecular beam epitaxy (MBE) fabricated films, respectively. Up to now, only Li et al.[11] presentindirect -indications for the realization of precipitate-free GeMn. Considering the current discussion on the magnetic properties of GeMn, a study of the crystal structure, exploring the degree of Mn dispersion that can be reached in Ge, would obviously be beneficial for the field.In this Letter, we present the first study relating structural parameters of precipitate-free Ge 0:95 Mn 0:05 films to magnetization data, providing new insights into the interpretation of the magnetic properties of GeMn. Although the incorporation of Mn does not induce explicit phase separation, nanometer-sized areas with increased Mn cont...

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Spintronics: recent progress and tomorrow's challenges

Cited by 49 publications

References 93 publications

Magnetic nanoparticles: recent advances in synthesis, self-assembly and applications

Magnetic nanoparticles: recent advances in synthesis, self-assembly and applications

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

Clustering in a Precipitate-Free GeMn Magnetic Semiconductor

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