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ABSTRACT: Protruding nanostructure is produced in the single layer of Cu(x)Au(1 - x) surface alloy grown on Cu(001) due to the mismatch strain which has been utilized as a template to tune the magnetic anisotropy of overlays recently. The protrusion network was investigated by in situ scanning tunneling microscopy (STM) combined with low energy electron diffraction (LEED) as a function of the stoichiometry. The measurement revealed the structure of the protrusion and its correlation with the composition. Interestingly, we observed a twin-domain phase of the protrusion when the film approaches the fully hetero-epitaxial range.
Journal of Physics Condensed Matter 10/2010; 22(39):395007. · 2.55 Impact Factor
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ABSTRACT: Protruding nanostructure is produced in the single layer of CuxAu1 − x surface alloy grown on Cu(001) due to the mismatch strain which has been utilized as a template to tune the magnetic anisotropy of overlays recently. The protrusion network was investigated by in situ scanning tunneling microscopy (STM) combined with low energy electron diffraction (LEED) as a function of the stoichiometry. The measurement revealed the structure of the protrusion and its correlation with the composition. Interestingly, we observed a twin-domain phase of the protrusion when the film approaches the fully hetero-epitaxial range.
Journal of Physics Condensed Matter 09/2010; 22(39):395007. · 2.55 Impact Factor
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B. F. Ding,
Y Yao,
X. Y. Sun,
Z. Y. Sun,
X. D. Gao,
Z. T. Xie,
Z. J. Wang,
X. M. Ding,
Y Z Wu, X F Jin,
C. Q. Wu,
X. Y. Hou
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ABSTRACT: Magnetoelectroluminescence (MEL) of organic semiconductor has been experimentally tuned by adopting blended emitting layer consisting of both hole and electron transporting materials. A theoretical model considering intermolecular quantum correlation is proposed to demonstrate two fundamental issues: (1) two mechanisms, spin scattering and spin mixing, dominate the two different steps respectively in the process of the magnetic field modulated generation of exciton; (2) the hopping rate of carriers determines the intensity of MEL. Calculation successfully predicts the increase of singlet excitons in low field with little change of triplet exciton population. Comment: 16 pages, 4 figures
11/2009;
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ABSTRACT: With continuous variable composition, an artificial pseudomorphic template of 1 ML Cu1−xAux was achieved by epitaxial growth on Cu(001), in which the magnetic anisotropy and the spin reorientation transition of Ni films were investigated in situ. The result clearly indicates that the strain induced protruding nanostructures at the interface dominates in tuning the magnetic anisotropy, while the interface chemistry plays a minor role.
Applied Physics Letters 11/2009; 95(19):192506-192506-3. · 3.84 Impact Factor
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ABSTRACT: The kinetic regime of step motion on the Si(111) (1 × 1) surface is determined from observations of island decay with low-energy electron microscopy (LEEM). We have investigated the island decay on the tops of mounds fabricated by a photolithographic method. Prefabricated mounds serve as controllable and reproducible island sources and platforms for decay. Island area during decay exhibits the expected power-law dependence on time, with exponent, α, that is indicative of the kinetic regime. In order to overcome the basic problem of realizing the thermodynamic limit of island decay on an infinite terrace, the power-law decay exponent is extrapolated to vanishing island (r)—to—terrace (R) radius ratio, r/R = 0. The dependence of α upon r/R suggests that island decay kinetics is intermediate between the diffusion-limited (DL) and attachment/detachment-limited (ADL) regimes. Copyright © 2006 John Wiley & Sons, Ltd.
Surface and Interface Analysis 11/2006; 38(12‐13):1632 - 1635. · 1.18 Impact Factor
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ABSTRACT: Permalloy with a body-centered-cubic structure has been grown on GaAs(001) by molecular beam epitaxy. Its magnetism, Curie temperature, and magnetic anisotropy are determined experimentally and compared to those of conventional face-centered-cubic Permalloy. Unexpectedly the vanishing magnetic cubic anisotropy in Permalloy is found to be independent of its atomic structure but depends only upon the stoichiometry of Fe and Ni in the FexNi1-x alloy. This observation is further investigated and confirmed by first-principles electronic band calculations, which help to understand the long-standing issue of why Permalloy should be a soft magnet.
Physical Review Letters 09/2006; 97(6):067203. · 7.37 Impact Factor
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ABSTRACT: The first normal emission experiment result on bcc Ni ultrathin film is presented in comparison with the one on fcc Ni. Its agreement with band structure calculation, by supplementing our former results on the magnetic properties of bcc Ni, verifies from the electronic viewpoint the successful epitaxy of this metastable phase of Ni which doesn't exist in nature.
05/2005;
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C S Tian,
D Qian,
D Wu,
R H He,
Y Z Wu,
W X Tang,
L F Yin,
Y S Shi,
G S Dong, X F Jin,
X M Jiang,
F Q Liu,
H J Qian,
K Sun,
L M Wang,
G Rossi,
Z Q Qiu,
J Shi
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ABSTRACT: The body-centered-cubic (bcc) phase of Ni, which does not exist in nature, has been achieved as a thin film on GaAs(001) at 170 K via molecular beam epitaxy. The bcc Ni is ferromagnetic with a Curie temperature of 456 K and possesses a magnetic moment of 0.52+/-0.08 micro(B)/atom. The cubic magnetocrystalline anisotropy of bcc Ni is determined to be +4.0x10(5) ergs x cm(-3), as opposed to -5.7x10(4) ergs x cm(-3) for the naturally occurring face-centered-cubic (fcc) Ni. This sharp contrast in the magnetic anisotropy is attributed to the different electronic band structures between bcc Ni and fcc Ni, which are determined using angle-resolved photoemission with synchrotron radiation.
Physical Review Letters 05/2005; 94(13):137210. · 7.37 Impact Factor
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ABSTRACT: Spin-dependent electron reflection from a Cu thin film grown on Co/Cu(001) was investigated using spin-polarized low-energy electron microscopy (SPLEEM). Fabry-Pe rot type interference was observed and is explained using the phase accumulation model. SPLEEM images of the Cu overlayer reveal magnetic domains in the Co underlayer, with the domain contrast oscillating with electron energy and Cu film thickness. This behavior is attributed to the spin-dependent electron reflectivity at the Cu/Co interface which leads to spin-dependent Fabry-Pe rot electron interference in the Cu film.
Physical Review Letters 02/2005; 94(2):027201. · 7.37 Impact Factor
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ABSTRACT: Magnetic stripe domains in the spin reorientation transition region are investigated in (Fe/Ni)/Cu(001) and Co/Cu/(Fe/Ni)/Cu(001) using photoemission electron microscopy. For (Fe/Ni)/Cu(001), the stripe domain width decreases exponentially as the Fe/Ni film approaches the spin reorientation transition point. For Co/Cu/(Fe/Ni)/Cu(001), the Fe/Ni stripe orientation is aligned with the Co in-plane magnetization, and the stripe domain width decreases exponentially with increasing the interlayer coupling between the Fe/Ni and Co films. By considering magnetic stripes within an in-plane magnetic field, we reveal a universal dependence of the stripe domain width on the magnetic anisotropy and on the interlayer coupling.
Physical Review Letters 10/2004; 93(11):117205. · 7.37 Impact Factor
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ABSTRACT: A prototype Hamiltonian for the generic patterned magnetic structures, of dipolar interaction with perpendicular anisotropy, is investigated within the finite-size framework by Landau-Lifshift-Gilbert classical spin dynamics. Modifications on the ground state phase diagram are discussed with an emphasis on the disappearance of continuous degeneracy in the ground state of in-plane phase due to the finite lattice size effect. The symmetry-governed ground state evolution upon the lattice size increase provides a critical insight into the systematic transition to the infinite extreme.
09/2004;
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ABSTRACT: Ni/Fe/Co/Cu(100) system was studied using photoemission electron microscope. By analyzing element specific domain images, we found that there exists oscillatory interlayer coupling between the Co and Ni layers across the fcc Fe layer. With the thickness and temperature dependent studies, we found strong evidence that the Fe layers at both the Fe/Co and Fe/Ni interfaces are ferromagnetically ordered in the 4–12 ML thickness range, and that the ferromagnetically ordered layer at the Fe/Ni interface disappears as the temperature exceeds the Curie temperature of the Ni layer. Moreover, the oscillatory interlayer coupling between the Co and Ni layers results in an oscillation of the Ni layer Curie temperature.
Phys. Rev. B. 05/2002; 65(21).
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X. F. Jin
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ABSTRACT: An ab initio linearized augmented plane-wave method has been employed to calculate the electronic and magnetic structures of both face-centered-cubic and body-centered-cubic Fe1-xPdx alloys with x=0.25, 0.50, and 0.75, respectively. Decreasing the Pd content in Fe1-xPdx alloy from x=1, the magnetic ordering of fcc Fe1-xPdx changes from paramagnetism to ferromagnetism, ferrimagnetism, and finally to antiferromagnetism. However, the magnetism of bcc Fe1-xPdx changes simply from paramagnetism to ferromagnetism.
Phys. Rev. B. 04/2002; 65(17).
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ABSTRACT: For Fe films epitaxially grown on Cu(100) at 300 K, the total magnetic moment as a function of film thickness and its temperature dependence have been investigated in situ with a multitechnique approach. The results exclude the collinear type-1 antiferromagnetic configuration as the magnetic structure for face-centered-cubic Fe films on Cu(100). It is proposed that a spin-density-wave state is responsible for the magnetic structure.
Physical Review Letters 12/2001; 87(22):227204. · 7.37 Impact Factor
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ABSTRACT: The structure and magnetism of Co1−xMnx films grown on GaAs(001) substrates were characterized by reflection high energy electron diffraction and magneto-optical Kerr effect measurements. It is found that the Co-rich and Mn-rich films exist in body-centered-cubic and face-centered-cubic structures, respectively. Meanwhile, the Co1−xMnx films show ferromagnetism whenever the structure is bcc, but they show antiferromagnetism or paramagnetism whenever the structure is fcc. This strong correlation established between the structure and magnetism was further studied and confirmed by an ab initio electron linearized augmented-plane-wave calculation with the local-spin-density approximation. © 2001 American Institute of Physics.
Journal of Applied Physics 12/2000; 89(1):521-523. · 2.17 Impact Factor
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X. F. Jin
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ABSTRACT: Growth and magnetism of ultrathin Fe films on Pd(100) have been studied in situ by reflection high-energy electron diffraction, scanning tunneling microscope, and magneto-optical Kerr effect technique. It is found that the growth at the initial stage is in the layer-by-layer mode and the magnetic hysteresis loops are detectable only when the Fe films are thicker than 1.3 monolayer (at 300 K) and 0.5 monolayer (at 55 K).
Phys. Rev. B. 10/1999; 60(16).
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ABSTRACT: Epitaxial structure of Co on GaAs(0 0 1) is studied by cross section high resolution transmission electron microscope. A bilayer structure is confirmed in the Co thin-film, where a body-centered-cubic (BCC) phase near the interface and a two-domain hexagonal-close-packed (HCP) phase on the top. Using the magneto-optical Kerr effect (MOKE) measurement, the in-plane magnetic anisotropy of the BCC phase is determined as a fourfold symmetry with easy axes along the [1 0 0] directions. Strongly depending on the: growth temperature, the two-domain HCP phase shows either a uniaxial symmetry along the [1 1 0] direction or a fourfold symmetry with easy axes along the [1 0 0] directions. (C) 1999 Elsevier Science B.V. All rights reserved.
Journal of Magnetism and Magnetic Materials 01/1999; 198-99:297-299. · 1.78 Impact Factor
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ABSTRACT: Epitaxial growth of Co on GaAs(001) and its in-plane magnetic anisotropy are studied using reflection high-energy electron diffraction, a high-resolution transmission electron microscope, and the magneto-optical Kerr effect. In the initial and final stages of growth, Co exists in single-crystalline body-centered-cubic (bcc) and hexagonal-closed-packed (hcp) phases, respectively, while in the middle stage the coexistence of the bcc and hcp structures is observed. For the bcc Co thin films on GaAs(001), a fourfold in-plane magnetic anisotropy with easy axes along the [100] directions is realized and discussed. [S0163-1829(98)04915-7].
Physical Review B. 01/1998; 57(19):11935-11938.
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ABSTRACT: Ultrathin Ni films in Cu/Ni/Cu001 bilayers and exchange coupled Ni films in Ni/Cu/Ni/Cu001 trilayers are investigated by magnetization induced second harmonic generation MSHG. The results are analyzed in a model of localized nonlinear polarizabilities at the interfaces. We show that antiferromagnetic coupling in the Ni/Cu/Ni trilayers is observable with MSHG due to the presence of quantum well states QWS's in the Cu layer. The influence of the QWS's on the SHG from a Ni film in a Cu/Ni/Cu001 bilayer is weaker compared to the case of Fe or Co bilayers.
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ABSTRACT: The formation of the Yb/InP(110) interface is studied by synchrotron radiation electron spectroscopy. Chemical reactions at the interface lead to the formation of an intermixed region of ternary composition. At increasing coverages two distinct intermetallic phases grow out of the mixed region: islands of a YbP phase and a layer of metallic YbIn alloy.
Surface Science.
