Magneto Transport and Quantum Effects in Electron Systems

(1)有机导体中的角度相关磁阻振荡(ADMRO)效应：(BEDT-TTG)_2KHg(SCN)_4和(BEDT-TTG)_2NH_4HG(SCN)_4有机导体中观察到了角度相关的振荡磁阻效应。我们通过两轴旋转测量了样品在强磁场中的角度依赖关系，阐明了后者的ADMRO是由调制的柱面费米面产生的标准振荡磁阻，而后者的ADMRO是由一对开放的费米片引起的。我们还进行了模型计算，定量地再现了后一种体系的ADMRO轨迹。(2)合成层状金属-SbCl5-插层石墨层中的ADMRO效应。分析了ADMRO效应和Shubnikov-de Haas效应对费米面的影响，认为费米面是一种复杂的区域折叠效应和磁击穿效应。(3)在GaAs/AlGaAs超晶格的剪裁费米面中的ADMRO效应。我们设计并制作了GaAsAlGaAs超晶格中的柱状费米面，证明了ADMRO最明显的发生在平面外的电阻率上。(4)调制磁场中的磁输运。我们从理论上分析了一维调制磁场对二维电子气的影响。我们利用铁磁性物质制成的栅门进行了实验尝试。

The following are the main research accomplishments of this project :(1)Angular dependent magnetoresistance oscillation(ADMRO) effect in organic conductors.Angular dependent oscillatory magnetoresistance has been observed in organic conductors, (BEDT-TTG)_2KHg(SCN)_4 and (BEDT-TTG)_2NH_4Hg(SCN)_4. We have performed precise measurements of the angular dependence by two-axis rotation of samples in high magnetic fields to clarify that the ADMRO in the latter system is a standard one arising form a modulated cylindrical Fermi surface, while that in the latter is attributed to a pair of open Fermi sheet. We have also made a model calculation which reproduced the ADMRO traces of the latter system quantitatively.(2)ADMRO effect in synthetic layred metal --- SbCl_5-intercalated graphiteWe have also observed the ADMRO in intercalated graphite. Analysis of both the ADMRO and the Shubnikov-de Haas effect powerful means of reconstruction of the Fermi surface, which is known to be complex in this system due to zone folding effect and magnetic breakdown effect.(3)ADMRO effect in tailored Fermi surface of GaAs/AlGaAs superlattice.We have designed and fabricated cylindrical Fermi surface in GaAs/AlGaAs superlattice and demonstrated that the ADMRO occurs most distinctly in the out-of-plane resistivity.(4)Magnetotransport in modulated magnetic field.We have theoretically analyzed the effect of one-dimensionally modulated magnetic field on two-dimensional electron gas. We have made an experimental attempt by use of a grid gate made of ferromagnetic substances.