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University of Nebraska - Lincoln

Si-Hwang Liou Publications

2001

Articles 1 - 4 of 4

Full-Text Articles in Physics

Electronic-Structure Modifications Induced By Surface Segregation In La0.65Pb0.35Mno3 Thin Films, C.N. Borca, B. Xu, T. Komesu, H.-K. Jeong, M.T. Liu, Sy_Hwang Liou, Shane Stadler, Y. Idzerda, Peter A. Dowben Dec 2001

Electronic-Structure Modifications Induced By Surface Segregation In La0.65Pb0.35Mno3 Thin Films, C.N. Borca, B. Xu, T. Komesu, H.-K. Jeong, M.T. Liu, Sy_Hwang Liou, Shane Stadler, Y. Idzerda, Peter A. Dowben

Si-Hwang Liou Publications

Using spin-polarized inverse photoemission and X-ray absorption spectroscopy techniques, we show that the electronic structure of La0.65Pb0.35MnO3 thin films depends on the composition at the surface. With a gentle annealing procedure, the surface provides a maximum of 80% spin asymmetry at 0.5 eV above the Fermi level in spite of extensive Pb segregation. A heavily annealed (restructured) surface exhibits a reduced surface "ordering" temperature of 240 K (compared to the approximately 335 K bulk value) as well as a reduced spin asymmetry value of 40% at 0.5 eV above Fermi energy.


Magnetic Nanodot Arrays Produced By Direct Laser Interference Lithography, M. Zheng, M. Yu, Yi Liu, Ralph Skomski, Sy_Hwang Liou, David J. Sellmyer, V.N. Petryakov, Yu K. Verevkin, N.I. Polushkin, N. N. Salashchenko Oct 2001

Magnetic Nanodot Arrays Produced By Direct Laser Interference Lithography, M. Zheng, M. Yu, Yi Liu, Ralph Skomski, Sy_Hwang Liou, David J. Sellmyer, V.N. Petryakov, Yu K. Verevkin, N.I. Polushkin, N. N. Salashchenko

Si-Hwang Liou Publications

Periodic magnetic nanodot arrays have been produced on an area as large as 1 cm×1 cm by direct nanolithography using interferometric laser radiation. The dots are formed by the local annealing of sputtered amorphous Co–C films in regions where the laser intensity is highest. At room temperature the dots exhibit ferromagnetic order and are embedded in a paramagnetic matrix. The onset of room-temperature ferromagnetism is caused by nanoscale chemical and morphological changes during dot formation and reflects the phase separation of magnetic Co-rich clusters. The present single-step nanolithography is potentially an efficient method for fabrication of patterned magnetic ...


Ferromagnetic Co-C Nanodot Arrays Produced By Direct Interferometric Laser Annealing, M. Zheng, M. Yu, Yi Liu, Ralph Skomski, David J. Sellmyer, V.N. Petryakov, Yu. K. Verevkin, Nikolay Polushkin, N.N. Salashchenko Jul 2001

Ferromagnetic Co-C Nanodot Arrays Produced By Direct Interferometric Laser Annealing, M. Zheng, M. Yu, Yi Liu, Ralph Skomski, David J. Sellmyer, V.N. Petryakov, Yu. K. Verevkin, Nikolay Polushkin, N.N. Salashchenko

Si-Hwang Liou Publications

Magnetic properties of Co-C nanodot arrays produced by direct interferometric laser annealing are investigated by magnetic force microscopy (MFM) and magnetization measurements. The dots are formed by locally annealing sputtered amorphous Co-C films in regions where the laser intensity is highest. As-sputtered Co-C films do not exhibit ferromagnetic order at room temperature, but MFM shows that the dots become magnetic upon annealing, possibly due to the agglomeration or phase separation of Co-rich clusters. The dots are embedded in either a paramagnetic or weakly magnetic matrix. The magnetic properties of the generated pattern can be changed by varying the laser power ...


Magnetic Properties And Nanostructures Of Composite, M.L. Yan, Yi Liu, M.J. Yu, Sy_Hwang Liou, David J. Sellmyer Jul 2001

Magnetic Properties And Nanostructures Of Composite, M.L. Yan, Yi Liu, M.J. Yu, Sy_Hwang Liou, David J. Sellmyer

Si-Hwang Liou Publications

Nanocomposite CoχPt100100-χ :C thin films with χ = 57 and χ = 50 were prepared by magnetron sputtering. Structures and activation volumes were studied systematically in order to better understand the magnetic behavior.We found that activation volumes of these two samples were almost the same. However, physical grain sizes of these two samples were different. Magnetic grains in the sample with equiatomic Co and Pt composition were almost independently switched and magnetic grains in the sample with higher Co content were exchange coupled and switched together. The reduction of the physical grain size in the sample does ...