摘要:

AbstractThe eigenstate calculation of quantum‐wire mesoscopic structures with quasi‐bound geometry is reported. In this geometry, electron wave packets are confined quantum mechanically into an effective potential cavity created by the crossing of quantum wells.First, a variety of quasi‐bound quantum wire structures is presented. Subsequently, the eigenenergies and the eigenfunctions are analyzed numerically by using a two‐dimensional finite element method (2‐D FEM). In this analysis, effects due to the finiteness of the barrier height are studied in contrast to earlier simple models where the height is assumed to be infinite.Structural dependencies of the eigenstates show evidence of the critical parity selectivity for wave functions trapped in the quasi‐bound quantum wire system. A comparative study of analysis methods is made as well. Comparison of the results obtained by the 2‐D FEM with those by the weighted potential method shows the limitation of the latter reproduced approach to the pr

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAcicular barium ferrite fine particles were successfully fabricated by sintering a mixture of Ba(OH)28H2O and acicular α‐FeOOH at a temperature of 500 to 1200°C for 1 hr in air and then rapidly cooled down. For sintering temperatures below 800°C, no magnetization was found. However, with increasing temperature beyond 900°C, the magnetization increased significantly in accordance with the formation of hexagonal barium ferrite. The coercivity increased for sintering at 900 to 1000°C and then decreased at 1100 to 1200°C where a significant grain growth was observed.Acicular barium ferrite fine particles with an atomic ratio 1 : 10 between Ba and Fe ions sintered at 1000°C were found to consist of particles of about 0.7‐μm length and an aspect ratio of about 7, which exhibit the magnetization and coercivity of 61 emu/g (61 A.m2/kg) and 3990 Oe (317.5 kA/m), respectively. Coated‐films were fabricated by dispersing barium ferrite fine particles thus obtained in resin solution, which were then coated onto polyester films.The squareness ratio of nonoriented films for the vertical field direction is larger than that for acicular barium ferrite fine particles, and the films were more easily magnetized along the film normal. When the magnetic field was applied along the film normal at the time of drying the film, the sample can easily be magnetized also. This result seems to indicate the possibility of barium ferrite‐coated films for vertical magnetic recording media. The major axis of acicular barium ferrite fine particles was found to be in the film plane and the easy axis for magnetization is along

ISSN:8756-663X    

DOI:10.1002/ecjb.4420760212

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY