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Your search keyword '"Pi, U.H.' showing total 10 results
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10 results on '"Pi, U.H.'

7. Domain nucleation and growth of La(sub 0.7)Ca(sub 0.3)MnO(sub 3-delta)/LaAlO3 films studied by low temperature magnetic force microscopy

Author

Liebmann, M., Kaiser, U., Schwarz, A., Wiesendanger, R., Pi, U.H.;, Noh, T.W, Khim, Z.G, and Kim, D.-W.

Subjects
Magnetic fields -- Research, Oxygen -- Magnetic properties, Oxygen -- Research, Calcium compounds -- Magnetic properties, Calcium compounds -- Research, Nonferrous metals -- Magnetic properties, Nonferrous metals -- Research, Physics
Abstract

(001) substrate as a function of film thickness (50 and 100 nm) and oxygen content (optimum and reduced) is investigated using magnetic force microscopy. The domain nucleation and growth takes place by discrete reorientation of regions that have diameters similar to the final domain width.

Published
2003

8. Investigation on hydrogen annealing effect for various ferroelectric films by electrostatic force microscope

Author

Sungchul Shin, Tae Won Noh, Da-Seul Kim, B.S. Kang, Z. G. Khim, and U.H. Pi

Subjects
Materials science, Hydrogen, business.industry, Annealing (metallurgy), Electrostatic force microscope, Bismuth titanate, General Physics and Astronomy, Mineralogy, chemistry.chemical_element, Surfaces and Interfaces, General Chemistry, Condensed Matter Physics, Ferroelectricity, Surfaces, Coatings and Films, Scanning probe microscopy, chemistry.chemical_compound, chemistry, Optoelectronics, Thin film, business, Forming gas
Abstract

Scanning probe microscope with a dc bias and an ac modulation signal applied to the probing tip has been quite successful for investigating the characteristics in a sub-micron scale for the high density ferroelectric memory application field. The degradation of ferroelectric films—PbZr 0.4 Ti 0.6 O 3 (PZT) and Bi 3.25 La 0.75 Ti 3 O 12 (BLT)—caused by the hydrogen forming gas annealing is investigated in a microscopic scale by using an electrostatic force microscope (EFM). From the first harmonic signal of EFM, we obtained different polarization behaviors from as-grown and hydrogen-annealed ferroelectric films. We found that the hydrogen forming gas annealing is degrading the ferroelectric film with no catalyst top electrode on top of the film. It is believed that the annealing process causes the diffusion of hydrogen into the ferroelectric film resulting in the destruction of polarization in these materials. We speculate that the different degradation behavior among these materials (PZT and BLT) is due to the different cohesivity of hydrogen in these materials.

Published
2002
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10. Tilted magnetization of a <f>La0.7Sr0.3MnO3/LaAlO3</f> (001) thin film

Author

Liebmann, M., Kaiser, U., Schwarz, A., Wiesendanger, R., Pi, U.H., Noh, T.W., Khim, Z.G., and Kim, D.-W.

Subjects
*MAGNETIZATION, *LANTHANUM compounds, *THIN films, *FERROMAGNETIC materials
Abstract

A La0.7Sr0.3MnO3 thin film epitaxially grown on a LaAlO3 (001) substrate by pulsed laser deposition has been investigated by means of low-temperature magnetic force microscopy under high stability conditions. The ferromagnetic film exhibits a stress-induced perpendicular easy axis of magnetization. The domain structure was imaged at zero field after (i) thermal demagnetization, (ii) saturation in an in-plane field and (iii) saturation in an out-of-plane magnetic field, respectively. Stripe domains were observed in all cases, however, contrast and domain width are increased after out-of-plane saturation while alignment of stripe domains in field direction occurs after in-plane saturation. A quantitative analysis of the image contrast suggests a variable in-plane component of the magnetization, dependent on the magnetic history of the sample. Calculations of domain width and contrast from the relevant energy contributions are compared with experimental results. [Copyright &y& Elsevier]

Published
2004
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