標題: Liquid crystal surface alignments by using films composed of magnetic nanoparticles - art. no. 691104
作者: Pan, Ru-Pin
Wu, Hsin-Ying
Hsieh, Cho-Fan
電子物理學系
Department of Electrophysics
關鍵字: liquid crystal;surface alignment;iron oxide;magnetic nanoparticles;ferrimagnetic thin film;ion beam sputtering;magnetization;polar anchoring strength
公開日期: 2008
摘要: A method for liquid crystal surface alignment by using a one-step, ion beam sputtering on glass substrates is demonstrated. Pre-coating by polyimide is not necessary. We use a diode-type sputter to treat the glass substrates with Ar ion-beam. The homeotropic alignments for nematic liquid crystals are achieved. The alignments are characterized by using the polarizing optical microscope and the conoscope. To find out the alignment mechanism, the studies by using super conducting quantum interference device and scanning probe microscopy are carried out. The surveyed surface morphology reveals that the films are amorphous and composed of nanoparticles with dimensions around 30 nm. The magnetization anisotropy of the sputtered magnetic films is analyzed. The polar anchoring strengths of the coated films with different thicknesses are measured and compared with their saturation magnetization. We deduce that the homeotropic alignment is achieved due to the orientation of the diamagnetic nematogenic molecules in the magnetic field caused by the gamma-Fe2O3 ferrimagnetic thin films. A simple model of alternatively distributed magnetic moments with opposite direction is proposed. The profile of magnetic field strength near the surface is then calculated to compare with the measured alignment strength.
URI: http://hdl.handle.net/11536/30375
http://dx.doi.org/10.1117/12.762985
ISBN: 978-0-8194-7086-7
ISSN: 0277-786X
DOI: 10.1117/12.762985
期刊: EMERGING LIQUID CRYSTAL TECHNOLOGIES III
Volume: 6911
起始頁: 91104
結束頁: 91104
Appears in Collections:Conferences Paper


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