Y. J. Wang

Magnetic properties of nanosized MnFe2O4 particles

Nanosized MnFe2O4 particles were prepared by chemical ultrasonic emulsion method. The as-prepared sample was found to be in amorphous state and showed spin-glass behavior at low temperature. The Curie temperature of the annealed sample is 160 K higher than that of the bulk material, which is thought to be due to finite-size scaling and also may be related to a nonequilibrium cation distribution

Effects of the crystal structure on electrical and optical properties of pyrite FeS2 films prepared by thermally sulfurizing iron films

Based on experimental results and theoretical analysis effects of the crystal structure on the optical and electrical properties of pyrite FeS2 films produced by thermally sulfurizing iron films at various temperatures have been systematically studied. The results indicate that the crystal structure and some related factors, such as the crystallization and the stoichiometry, remarkably influence the optical and electrical performances of the pyrite films. It is also shown that the preferred orientation of the crystal grain plays a major role in determining the crystal structure and the optical and electrical properties of the pyrite FeS2 films. Also we find that it is the crystal grains, rather than the particles that exercise a decisive influence on the electrical performance of pyrite films

Magnetic properties of nanostructured Mn oxide particles

Nanostructured Mn oxide particles with an average size of about 7 nm have been prepared by a microemulsion method. X-ray diffraction analysis indicates that the particles possess orthorhombic structure of MnO(OH). The particles are ferromagnetic at low temperature. The Curie temperature is about 35 K and each MnO(OH) molecule generates a magnetic moment of about 0.7 μB. The appearance of the ferromagnetism at low temperature may result from size effect.

Enhanced coercivity of exchange-bias Fe/MnPd bilayers

We present detailed studies of the enhanced coercivity of exchange-bias bilayer Fe/MnPd, both experimentally and theoretically. We have demonstrated that the existence of large higher-order anisotropies due to exchange coupling between different Fe and MnPd layers can account for the large increase of coercivity in the Fe/MnPd system. The linear dependence of coercivity on inverse Fe thickness is well explained by a phenomenological model by introducing higher-order anisotropy terms into the total free energy of the system.

Oestrogen-related receptor alpha inverse agonist XCT-790 arrests A549 lung cancer cell population growth by inducing mitochondrial reactive oxygen species production.

Objective:  Although oestrogen‐related receptor α (ERRα) is primarily thought to regulate energy homeostasis, it also serves as a prognostic marker for cancer. The aim of this study was to investigate any connection between ERRα activity and cell population growth.

Doping dependence of the upper critical field in La2−xSrxCuO4 from specific heat

The low-temperature specific heat of La2- xSrxCuO4 (LSCO) single crystals in the magnetic field H up to 12 T has been examined over a wide range of doping (0.063≤p≤0.238). From this we have mapped the upper critical field Hc2 of LSCO across the entire superconducting diagram. It is found that the Hc2 shows a doping dependence similar to that of the critical temperature Tc. We have discussed the implications of the result and proposed that there may be an effective superconducting energy scale responsible for the Hc2 behavior in the underdoped region.

Investigation of exchange bias in FeMnC/FeMn bilayers

The exchange bias (EB) effect and magnetic domain structures of FeMnC/FeMn bilayers prepared by a facing target sputtering system were studied. Unusual doubly shifted hysteresis loops were observed in a series of FeMnC/FeMn bilayers when different magnetic fields were applied to induce the exchange bias. The temperature dependences of the double shifted loops were measured and the ferromagnetic resonance measurement reveals the existence of EB. The correlation between the microscopic domain structures and the magnetization reversal processes was discussed, which suggests that the domain structure distribution of the antiferromagnetic layer is responsible for the loop shift.

Magneto‐optical properties of MnBiAl thin films

Mn‐Bi‐Al thin films were produced by sequential evaporation of the constituents, followed by an anneal at 300 °C. The temperature and composition dependencies of the Kerr rotation angle, absolute reflectivity, and magnetic anisotropy were measured. The results show that, up to 30 at. % Al concentration, the thin films retain the pure MnBi hexagonal structure. Further, for suitable Al content, the films have the same large Kerr rotation as MnBi. Pure MnBi films exhibit perpendicular anisotropy at room temperature and in‐plane anisotropy for temperatures below 142 K. In contrast, the Al‐doped films prepared here have perpendicular anisotropy down to at least 85 K. The increased coercivities of the Al‐doped films are attributed to the occupation of grain‐boundary and interstitial sites of the NiAs‐type hexagonal structure by the Al atoms.

Perpendicular anisotropy dependence of oscillatory interlayer coupling behavior in [Pt/Co]5/Ru/[Co/Pt]5 multilayers

The experiments on the [t1Pt/0.4Co]5/(0.2–5.0)Ru/[0.4Co/t2Pt]5 (thickness unit is nm) multilayers with perpendicular anisotropy (PA) indicate that the interlayer coupling shows an antiferromagnetic (AF) and a ferromagnetic oscillatory behavior with the thickness of Ru spacer layers from 0 to 5.0 nm, and that the AF oscillations display a superposition of two different periods, which are 0.8 and 1.1 nm, respectively. Moreover, we found that the magnitude of AF coupling strength J is closely related to the magnitude of PA caused by varied thickness of nonmagnetic Pt layer. Our experimental results can be explained by Bruno’s electron-optics model.

Effects of the sulfur pressure on pyrite FeS2 films prepared by sulfurizing thermally iron films

The effect of sulfur vapor pressure in preparing the FeS2 films has been discussed and some incongruous views about sulfur pressure have been clarified in this paper based on experimental results and theoretical analysis. It is shown that lower sulfur pressures than the saturation value only result in poorer crystallization and worse performances, and in other words the FeS2 films could be optimized through improving the sulfur pressure till the saturation point. However for a certain temperature the sulfur pressure is limited by its saturated vapor pressure, and further increase of the sulfur quantity reacted with Fe films has little influence on the structure and properties of the pyrite films