Y. Z. Miao

Nanjing University, Nan-ching, Jiangsu Sheng, China

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Publications (21)36.63 Total impact

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    ABSTRACT: Magnetic measurements, ferromagnetic resonance, magneto-optical Kerr rotation and nuclear magnetic resonance have been used to study the spin polarization of nonmagnetic layers of Pd, Cu, Ag and Al in multilayers and sandwiches containing Fe, Co, FeCo and CoCr. The existence of the spin polarization of Pd, Cu, Ag and Al was demonstrated directly or indirectly.
    Journal of Magnetism and Magnetic Materials 01/1995; 140:533-534. · 2.00 Impact Factor
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    ABSTRACT: (BiDy)3Fe5O12 films were made in the amorphous state by rf magnetron sputtering from a sintered Bi2Dy1Fe5O12 ceramic target onto quartz substrates and studied by X-ray diffraction. The films were annealed at temperatures ranging from 500 to 700°C for 1 h in air and also at 650°C for different periods of time from 5 to 60 min. X-ray diffraction was used to determined the phase components of the samples. In the X-ray patterns, the amorphous films had two diffuse broad maxima in X-ray diffraction patterns centred at the double diffraction angles 2θ=31° and 52°, respectively. The films crystallized at 650°C and all the crystallized samples have a single phase of garnet. The FMR linewidth increased with the decreases in annealing temperature and annealing time. No FMR and EPR of Fe3+ were observed in the amorphous films even though they contained large amounts of Fe3+ ions, while the EPR of Fe3+ was observed in slide glass with the same gain.
    Journal of Magnetism and Magnetic Materials 01/1995; 139(s 1–2):115–118. · 2.00 Impact Factor
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    ABSTRACT: Compositionally modulated films (CMFs) of Fe/Cu and Fe/Ag, made by RF sputtering, were investigated with ferromagnetic resonance (FMR), nuclear magnetic resonance (NMR), and magneto‐optical (MO) spectroscopy. Evidence of spin polarization of the nonmagnetic layers, related to the interlayer coupling, was obtained. Direct evidence of the penetration of an exchange field and the spin polarization of the conduction electrons in the nonmagnetic Cu layers was obtained in Fe/Cu CMFs by NMR. Spin‐wave resonances were observed in Fe/Cu CMFs in FMR experiments, and the spin wave was found to be sustained by both the Fe and Cu sublayers. The MO spectra of Fe/Ag CMFs indicated that the conduction electrons of Ag are spin polarized and give an additional MO activity.
    Journal of Applied Physics 06/1994; · 2.21 Impact Factor
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    ABSTRACT: Crystalline Co spinel ferrite films were prepared by rf sputtering on glass substrates without buffer layer and annealed at temperatures from 400 to 600 °C for 2 h in air. (100) texture was obtained in these films. The anisotropy constant, magnetic hysteresis loops, and magneto‐optical Faraday spectra of the films were measured. The texture became poor when the films were annealed below 500 °C, but the perpendicular anisotropy constant K u , squareness ratio R=(Mr/Ms) ⊥ /(Mr/Ms) ‖ increased and showed peak values of 2.2×10<sup>5</sup> ergs/cm<sup>3</sup> and 0.94, respectively, at an annealing temperature T a =500 °C. For the film annealed at 600 °C (higher than the Curie temperature, 520 °C, of Co spinel ferrite), the texture recovered, but K u and R dropped. The Faraday rotation spectra of Co spinel ferrite films showed a broad peak centered around 720 nm. The peak value increased monotonically with increasing annealing temperature. These results may be related to the Co ion‐induced anisotropy and Co ion distribution in tetrahedral sites and octahedral sites.
    Journal of Applied Physics 06/1994; · 2.21 Impact Factor
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    ABSTRACT: Amorphous BaCoTiFe10O19 films have been prepared by the RF sputtering technique. The magnetic and magneto-optical properties, the structure and the effect of annealing have been investigated. The 4.2 K magnetization increases with increasing magnetic field and is not saturated at a high magnetic field of 65 kOe. Above 100 K the susceptibility obeys a Curie-Weiss law with a low Curie constant of 0.81 and a large negative Weiss constant of -350. The effective paramagnetic moment (2.54 mu B) for ion ions is much smaller than the theoretical moment. Amorphous BaCoTiFe10O19 films have a lower magnetization(1.5 emu g-1 at 1.5 K) and higher Curie temperature (850 K) and coercivity (700 Oe at room temperature) than crystalline bulk samples do. After annealing above 750 degrees C, amorphous samples crystallize into single M-type hexaferrite with a magnetization of 320 emu cm-3, a coercivity of 100 Oe and a magneto-optical Faraday rotation of 1 degrees mu m-1 at room temperature.
    Journal of Physics Condensed Matter 01/1994; 6(5):1047-1052. · 2.22 Impact Factor
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    ABSTRACT: (BiDy)Fe5O12 films in the amorphous state were made by rf magnetron sputtering from a sintered Bi2DyFe5O12 ceramic target onto quartz substrates and confirmed by x-ray diffraction. The films were annealed at different temperatures ranging from 500 to 800 °C for 1 h in air. The crystallization temperature was about 650 °C, as measured by DTA method. Magnetization M versus temperature relation of well crystallized films showed both a compensation temperature Tcomp (80 K) and Curie temperature TC (563 K). The M-T curve from 1.5 to 600 K of amorphous film showed no definite TC or Tcomp; M measured in a field of 20 kOe decreased monotonously. The Faraday rotation (500–700 nm) of amorphous films was small. The M and Faraday rotation (633 nm) increased rapidly at the crystallization temperature. The Bi ion induced peak (550 nm) in the Faraday spectra got higher with the increasing annealing temperature and was up to 9.14 degree/μm. The Faraday spectra of films annealed at 650 °C for different times showed that the films were well crystallized after annealing for 10 min. The optical absorption of the films in the visible region varied little during the transformation from amorphous to polycrystalline.
    Journal of Applied Physics 01/1994; 75. · 2.21 Impact Factor
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    ABSTRACT: The complex magneto‐optical Kerr rotation spectra of Fe/Cu and FeCo/Cu bilayers and compositionally modulated films (CMF) were studied experimentally and theoretically. In the bilayers, an enhancement of Kerr ellipticity ϵ k by a factor of 5 was observed at long wavelength side, while the Kerr rotation θ k can only be enhanced by a factor of 2 around the plasma edge of Cu. In the CMFs, ϵ k was enhanced by 60% but no θ k enhancement was observed. Theoretical analyses showed that both the magnitude of effective ϵ~ xye and the magnitude and signs of effective A e and B e are important for magneto‐optical enhancement.
    Journal of Applied Physics 10/1993; · 2.21 Impact Factor
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    ABSTRACT: Not Available
    Magnetics Conference, 1993. INTERMAG '93., Digest of International; 05/1993
  • 01/1993;
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    ABSTRACT: Theoretical and experimental studies of thetaK spectra demonstrated that the conduction electrons of Ag in Fe/Ag CMF are spin polarized and give an additional MO activity. In FeCo/Cu/FeCo sandwiches, an oscillation of thetaK with changing thickness of Cu was observed, which may indicate an oscillatory spin polarization of Cu layers.
    Journal of Magnetism and Magnetic Materials 01/1993; 126:541-543. · 2.00 Impact Factor
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    ABSTRACT: Bilayers Fe/Au‐Cu and Fe/Ag‐Au made by vacuum evaporation were studied. The magneto‐optical polar Kerr rotation and reflectivity spectra were measured in the region from 400 to 700 nm. In the magneto‐optical Kerr rotation spectra of bilayers Fe/Au‐Cu and Fe/Ag‐Au with the thickness of Fe layer less than the light penetration depth, there is a broad enhancement of the magneto‐optical polar Kerr rotation with a Kerr peak near the plasma edge in the reflectivity spectra of Au‐Cu and Ag‐Au alloys. The peak shifts toward the long wavelength side with increasing Cu and Au content in Au‐Cu and Ag‐Au alloys, respectively. Our results show that the composition of the reflector in our bilayer structures can shift the wavelength range of the magneto‐optical Kerr rotation enhancement. Interpretation and discussions are given.
    Journal of Applied Physics 03/1992; · 2.21 Impact Factor
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    ABSTRACT: In the magneto-optical polar Kerr rotation spectra of Fe/Au-Cu bilayers made by vacuum evaporation with the thickness of Fe layer less than the light penetration depth, a broad enhancement of the Kerr rotation spectra occurs near the absorption edge in the reflectivity spectra of Au-Cu alloys and shifts towards the longer wavelength side when the content of Cu in the Au-Cu reflector increases. For Fe/Al-Cu bilayers made by rf magnetron sputtering with a small content of Al in the Al-Cu reflector a peak occurs in its Kerr rotation spectrum. When the content of Al becomes larger the Kerr rotation increases with the decrease of wavelength monotonically and an enhancement occurs in the short wavelength region. A-M Center of Southeastern University, Washington, DC 20024, USA.
    Journal of Applied Physics 01/1992; 104:1015-1016. · 2.21 Impact Factor
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    ABSTRACT: The magneto-optical Kerr rotation in various bilayer, trilayer and multilayer films are studied experimentally and theoretically. In bilayers and trilayers the enhancement of Kerr rotation by a factor of two to five based on the reduction of effective optical constants has been achieved with a reasonable reflectivity. The enhancement can be realized in the whole wavelength region, from near IR to near UV. In Fe/Pd and FeSi/Cu multilayer films an additional magneto-optical activity related to the exchange polarization of Pd and Cu layers is observed. Multilayer films with broad opportunities for reducing effective optical constants and creating additional magneto-optical activities are demonstrated to be a promising area for finding new magneto-optical materials.
    Journal of Magnetism and Magnetic Materials 01/1992; · 2.00 Impact Factor
  • Y.B. Xu, H.R. Zhai, M. Lu, Y.Z. Miao, B.X. Gu
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    ABSTRACT: An approach is proposed and shown by numerical calculations to shift the enhancement peak of the magneto-optical Kerr rotation of the metallic bilayers of recent interest to the wavelength of semiconductor laser.
    Solid State Communications. 01/1992;
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    ABSTRACT: The experimental magneto-optical Kerr rotation spectra of Fe/Ag compositionally modulated films reported by Katayama et al. are studied theoretically. It is found that the free electrons of Ag are spin polarized. The magnitude of the polarization is about 1% with a direction opposite to that of Fe. The polarized Ag also gives rise to an additional magneto-optical activity as in Pt and Pd.
    Physics Letters A 01/1992; · 1.77 Impact Factor
  • H.R. Zhai, Y.B. Xu, M. Lu, Y.Z. Miao
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    ABSTRACT: It is shown that low optical constants of the reflecting substrate of metallic bilayers for magneto-optical Kerr effect (MOKE) enhancement can be obtained around wavelength 800 nm either in a thin noble metal layer or in a dielectronic/noble metal double layer reflector. Analyses also indicate that low optical constants can be obtained at any visible/near infrared wavelength with a dielectric/metal double layer. A method of designing the magnetic layers for MOKE enhancement is proposed.
    Journal of Magnetism and Magnetic Materials 01/1992; · 2.00 Impact Factor
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    ABSTRACT: Different thickness dependencies of the magneto‐optical Kerr effect of the magnetic (Co, Ni, and Fe)/nonmagnetic (air, glass, Cu, and W) bilayer structures were studied experimentally and theoretically, showing the complicated influence of the dielectric constants of the underlying substrate.
    Journal of Applied Physics 12/1991; · 2.21 Impact Factor
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    ABSTRACT: The magneto‐optical polar Kerr rotation spectra and reflectivity spectra in the wavelength region 400–700 nm are studied for Fe/PbTe and Fe/Pb bilayer films. Large Kerr rotation enhancement with high reflectivity was observed. The experimental data of reflectivity are nearly consistent with theoretical calculation using Fresnel’s equations. However, the observed Kerr rotation spectra behavior is quite different from that expected by macroscopic optical theory.
    Journal of Applied Physics 12/1991; · 2.21 Impact Factor
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    ABSTRACT: Bilayers Nd‐Fe/Cu and Nd‐Fe/Al made by vacuum evaporation were studied. The magneto‐optical Kerr effect (MOKE) and reflectivity spectra were measured. For Nd‐Fe/Cu with low Nd content and small thickness of Nd‐Fe layer there is a peak in the MOKE spectrum and a broad MOKE enhancement. The position is located near the plasma edge of Cu. When the content of Nd exceeds 37 at. %, there is no Kerr peak in the MOKE spectrum of Nd‐Fe/Cu. When the thickness of the magnetic layer is larger but still less than the light penetration depth, the position of the peak moves towards the long‐wavelength side. For Nd‐Fe/Al there is a broad enhancement in the short‐wavelength region, but no Kerr peak occurs no matter how the magnetic layer changes. The results presented show that the necessary conditions for MOKE enhancement in bilayers are suitable values of n and k of the reflector, whether the reflector has a plasma edge or not, and the enhancement also depends on the properties of the magnetic layer.
    Journal of Applied Physics 05/1991; · 2.21 Impact Factor
  • H. R. Zhai, Y. B. Xu, M. Lu, Y. Z. Miao
    physica status solidi (a) 03/1991; 124(1):67-. · 1.21 Impact Factor