X. F. Jin

Fudan University, Shanghai, Shanghai Shi, China

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Publications (51)137.54 Total impact

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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. · 2.36 Impact Factor
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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
    Physical review. B, Condensed matter 11/2009; · 3.77 Impact Factor
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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. · 3.79 Impact Factor
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    ABSTRACT: The magnetic anisotropy and interlayer coupling of epitaxially grown Ni/Cu/Co sandwich on Cu(100) have been studied in situ as a function of Cu and Ni thicknesses by magneto-optic Kerr effect. Oscillatory magnetic anisotropy of Ni layer is observed and attributed to the oscillatory interlayer coupling between the Ni and Co layers.
    Physical review. B, Condensed matter 01/2009; 80. · 3.77 Impact Factor
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    ABSTRACT: Co/NiO/Fe trilayers are grown on Ag(001) substrate using Molecular Beam Epitaxy (MBE). Element-specific magnetic domain images on both ferromagnetic (FM) Co and Fe layers and antiferromagnetic NiO layer are obtained using X-ray Magnetic Circular Dichrism (XMCD) and X-ray Linear Dichrism (XMLD), respectively. By comparing these magnetic domain images, we find that the Co-Fe interlayer coupling across the NiO spacer layer exhibits a transition from a 90^o-coupling to a collinear coupling as the NiO film thickness increases. This observation is shown to be directly related to the NiO magnetic structure and its interaction at the Co/NiO and NiO/Fe interfaces.
    03/2008;
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    ABSTRACT: The finite-temperature magnetism of Ni and permalloy in body-centered-cubic (bcc) and face-centered-cubic (fcc) phases is studied theoretically using ab initio supercell calculations and Green's function methods. The results confirm and explain the general experimental trend that the fcc phases have higher Curie temperatures than the bcc counterparts. In addition, the spin-wave stiffness constants of bcc-Ni and bcc-permalloy are predicted.
    Physical Review B. 02/2008; 77(5).
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    ABSTRACT: FexPd1-x films were epitaxially grown on Au(001). The structure changes from face-centered-cubic (fcc) to face-centered-tetragonal (fct) at x˜0.6, then to body-centered-cubic (bcc) at x˜0.85. Ferromagnetism shows up at 300 K when x is 0.06. The cubic magnetocrystalline anisotropy constant K switches from negative to positive as x increases to 0.34.
    Physics Letters A 01/2008; 372:1687-1690. · 1.77 Impact Factor
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    ABSTRACT: Molecular beam epitaxially grown Fe on GaAs(001) capped by Au overlayer with variable thickness had been investigated in situ by magneto-optical Kerr effect (MOKE). It is observed that the MOKE intensity as a function of Au film thickness decays much faster than that derived from the well-known Zak's theory. This can be explained by different optical parameters of ultrathin films from bulk values. It is also found that a minimum thickness of 1.4 nm Au is needed to effectively prevent the oxidation of Fe film at 300 K in atmosphere.
    Thin Solid Films 06/2007; 515(18):7290–7293. · 1.60 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. · 1.22 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. · 7.94 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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    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. · 7.94 Impact Factor
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    ABSTRACT: Spin reorientation transition (SRT) of Fe/Ni/Cu(001) was investigated using photoemission electron microscopy (PEEM). Stripe domains were imaged as a function of temperature to monitor the domain melting process. We found that the stripe domains melt in a narrow thickness range of the SRT region. This result indicates that the Curie temperature at the SRT point is lowered by the reduction of the magnetic anisotropy. In addition to the stripe domains, we observed a metastable phase of magnetic bubble domains in the SRT region, which may suggests the importance of higher order magnetic anisotropy in the SRT.
    03/2005;
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    ABSTRACT: Spin-dependent electron reflection from a Cu thin film grown on Co/Cu(001) was studied using Spin Polarized Low Energy Electron Microscopy (SPLEEM). We find that the electron reflectivity from the Cu thin film exhibits a Fabry-P'erot type interference. As the Cu thickness increases, the energies of the interference peaks decrease (or increase) for k-vector greater (or less) than half of the Brillouin zone (BZ) vector. This interference effect can be well explained using the phase accumulation model. Moreover, we observed spin-dependent reflectivity from the Cu thin film. SPLEEM images of the Cu film reveal the magnetic domain structure of the underlying Co film, with the domain contrast oscillating with the electron energy and the Cu film thickness. This observation is attributed to the spin-dependent reflectivity at the Cu/Co interface.
    03/2005;
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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. · 7.94 Impact Factor
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    ABSTRACT: FeMn∕Co∕Cu(001) films were epitaxially grown and investigated using photoemission electron microscopy and the surface magneto-optic Kerr effect. The FeMn antiferromagnetic order increases the Co film coercivity, switches the Co magnetization easy axis from the [110] direction to the [100] direction, and increases the Co film critical thickness at which the ferromagnetic transition occurs. The Néel temperature of the FeMn film increases with increasing FeMn film thickness. At room temperature, we constructed a magnetic phase diagram in the FeMnCo thickness plane to describe the FeMn and Co magnetic phases.
    Physical Review B 01/2005; 71(2). · 3.77 Impact Factor
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    ABSTRACT: Effect of Mn overlayer on the spin reorientation transition (SRT) of Ni/Cu(0 0 1) is investigated in situ by multi-functional techniques such as surface magneto–optic Kerr effect (SMOKE) measurement. It is found that the SRT thickness of Ni/Cu(1 0 0) shifts to thinner Ni thickness by ∼0.5 ML after covering the Ni film with 0.5 ML Mn.
    Journal of Magnetism and Magnetic Materials 01/2005; 286:497-500. · 1.83 Impact Factor
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    ABSTRACT: Magnetic stripe domains in Fe∕Ni∕Cu(001) were imaged and studied using photoemission electron microscopy. The stripe domain width decreases exponentially as the system approaches the spin reorientation transition (SRT) point. A reduction of the Curie temperature (TC) is observed within a narrow gap of the SRT region. For film with fixed thickness, the stripe domains below TC represent only part of the stripe phase due to a higher SRT temperature than TC.
    Physical Review B 01/2005; 71(22). · 3.77 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. · 7.94 Impact Factor
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    R. H. He, X F Jin
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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;