Author: Matthias GesterPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Structural and Magnetic Properties of Epitaxial Fe and Co Films on GaAs Substrates
Author: Matthias GesterStructural and Magnetic Properties of Ultrathin Epitaxial Fe Films on GaAs(001) and Related Semiconductor Substrates
Author: Gottfried WastlbauerGrowth of Epitaxial Fe and Co Ultrathin Films on GaAs and Study of Their Structural and Magnetic Properties
Author: Marco MadamiMagnetic Properties of Ultra Thin Epitaxial Fe Films on GaAs(001).
Author: J. G. TobinPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The magnetic properties of epitaxial Fe films on GaAs in the range of the first few monolayers have been the subject of a considerable number of investigations in recent years. The absence of magnetic signatures at room temperature has been attributed to the existence of a magnetic ''dead'' layer as well as superparamagnetism. By examining the temperature dependence of the magnetic linear dichroism of the Fe core level photoelectrons, we found that these ''non-ferromagnetic'' layers had in fact a Curie temperature, T{sub c}, substantially lower than room temperature, e.g., a T{sub c} of about 240K for thin films of a nominal thickness of 0.9 nm. The values of Curie temperature were sensitive to the initial GaAs substrate conditions and the thickness of the Fe over-layer with a layer of thickness of 1.25 nm showing a T{sub c} above room temperature. The data suggest that the ultrathin Fe films on GaAs(001) are ferromagnetic, although a weaker exchange interaction in the films lead to a substantial reduction in Curie temperature.
In-situ Study of Structural and Magnetic Properties of Epitaxial Fe/Cu Ultrathin Films
Author: Silvia TacchiInvestigations of the Epitaxial Growth and Characterization of High Perfection Magnetic Thin Films
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 43
Book Description
Methods of preparing high-perfection single crystalline films of 3d elements (including Fe, Co) and magnetic rare earths on semiconducting GaAs substrates have been investigated. The use of seed layers of Fe or Co (a few monolayers thick), deposited onto GaAs(001), followed by a Ag(001) film, provided a suitable template for Fe epitaxy. This method avoided interfacial chemical reactions between Fe and the semiconductor, at the expense of introducing coherency strain and tilted epitaxy of the Fe. In the case of rare earths, intermediate seed films of rare earth trifluorides, grown onto GaAs(111(-)) provided a template for growth of c-axis oriented rare earth films and sandwich structures. These methods have enabled the effects of coherency strain on magnetic properties of Fe and rare earths to be investigated. Using an automated X-ray photoelectron diffraction (XPD) system we have investigated the growth and interfacial mixing of several key epitaxial systems including Co/Pt, Co/Ag, NdF3/LaF3 and Pt/GaAs. Interfacial mixing in the interfaces of Co/Pt superlattices was confirmed, resulting in an alloyed region containing the ordered L12 phase: CoPt3. Spin-polarized photoelectron diffraction (SPPD) experiments on MnF2 suggest a new , high-temperature magnetic ordering transition at 380K which is 313K above the Neel temperature.
Epitaxial Nd-Fe-B films: Growth, texture, magnetism and the influence of mechanical elongation
Author: Ah Ram KwonPublisher: Cuvillier Verlag
ISBN: 3736930577
Category : Technology & Engineering
Languages : en
Pages : 110
Book Description
The work in this thesis focuses on the preparation of epitaxial Nd-Fe-B thin films using pulsed laser deposition for good hard magnetic properties. They are suitable for a basic understanding of the intrinsic magnetic properties. Compositional control was necessary to achieve phase formation with improved magnetic properties. Nd-Fe-B samples were prepared on single crystal MgO (001) substrates with different buffer layers in order to obtain good textures with different surface morphology. The smooth and continuous epitaxial films were suitable for performing magnetization measurements under stress. Although the magnetostriction is easily neglected in the Nd2Fe14B compound, distinguishable inverse magnetostriction was observed by conventional tensile elongation with a flexible substrate. As a result, anisotropic strain in the film, which breaks the in-plane symmetry, affected the opening angle during the spin reorientation. Therefore an elliptical distortion of the in-plane anisotropy below the spin reorientation temperature of Nd2Fe14B was obtained, whereas the transition temperature itself was not influenced significantly.
Handbook of Spin Transport and Magnetism
Author: Evgeny Y. TsymbalPublisher: CRC Press
ISBN: 1439803781
Category : Science
Languages : en
Pages : 797
Book Description
In the past several decades, the research on spin transport and magnetism has led to remarkable scientific and technological breakthroughs, including Albert Fert and Peter Grunberg's Nobel Prize-winning discovery of giant magnetoresistance (GMR) in magnetic metallic multilayers. Handbook of Spin Transport and Magnetism provides a comprehensive, bal
Spintronics Handbook, Second Edition: Spin Transport and Magnetism
Author: Evgeny Y. TsymbalPublisher: CRC Press
ISBN: 0429750889
Category : Science
Languages : en
Pages : 635
Book Description
Spintronics Handbook, Second Edition offers an update on the single most comprehensive survey of the two intertwined fields of spintronics and magnetism, covering the diverse array of materials and structures, including silicon, organic semiconductors, carbon nanotubes, graphene, and engineered nanostructures. It focuses on seminal pioneering work, together with the latest in cutting-edge advances, notably extended discussion of two-dimensional materials beyond graphene, topological insulators, skyrmions, and molecular spintronics. The main sections cover physical phenomena, spin-dependent tunneling, control of spin and magnetism in semiconductors, and spin-based applications.
Influence of Substrate Surface Reconstruction on the Growth and Magnetic Properties of Fe on GaAs(001).
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 7
Book Description
We have studied the magnetic and structural properties of epitaxial bcc Fe(001) films grown at 175 C on molecular-beam epitaxy-prepared GaAs(001)-2*4 and -c(4*4) reconstructed surfaces, with film thicknesses ranging up to ~30 ML (~43). We present measurements of the thickness-dependent evolution of the magnetic properties of the Fe films as determined by in situ magneto-optic Kerr effect. We find that the magnetic properties and growth mode are similar for both 234 and c(434) reconstructions, although the initial adsorption sites and island nucleation as measured by scanning tunneling microscopy are clearly dominated by the substrate surface reconstruction. The onset of room-temperature ferromagnetism occurs at 6 ML for growth on both GaAs surface reconstructions. At this coverage, the measured Curie temperature (100 C) is significantly reduced from that of bulk alpha-Fe (770 C). The anisotropy is dominated by a uniaxial component such that the two (110) axes are inequivalent for all coverages studied. Shape anisotropy does not appear to play a significant role.