Electronic Phases in Low-Dimensional Electron Systems under Ultra-High Magnetic Fields

超高磁场下低维电子系统中的电子相

基本信息

批准号：
12440083
负责人：
OSADA Toshihito
金额：
$ 9.92万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The purpose of this work is to find and to clarify new electronic phases which appear in low-dimensional electron systems under ultra-high magnetic fields beyond 100T. In the present work, we have tried to measure electric conduction under pulsed ultra-high magnetic fields with the width of several us, which have been generated by the electromagnetic flux compression method or the single-turn-coil direct discharge method. In order to overcome the experimental difficulties of huge induced voltage, huge discharge noise, and sample heating due to eddy current, we have developed techniques for RF transport measurement and microfabrication of samples.1. Electron Correlation under Ultra-High Magnetic FieldsHigh-field magnetotransport measurements for graphite and bismuth have revealed that the posions of the Shubnikov-de Haas oscillations near the high-magnetic-field quantum limit deviate from those expected from low-field oscillations. This fact strongly suggests that the self energy correc … More tion due to electron correlation is enhanced at high-field quantum limit where the electron orbit becomes smaller than the electron distance.2. Bloch Electron Systems under Ultra-High Magnetic FieldsIn quasi-one-dimensional conductor NbSe_3 which shows double Peierls transitions, one small thin electron pocket remains at the low-temperature phase. We have found that the magnetoresistance monotonously decreases in the high-field quantum limit where all electrons lie in the lowest Landau level. This anomalous behavior reflects the Harper broadening of the lowest Landau level due to the magnetic breakdown across the CDW gap.3. Two-Dimensional Electron System under Ultra-High Magnetic FieldsIn order to investigate the high-field phases in quantum Hall systems, we have developed the techniques for RF transport measurement in quantum Hall systems whose impedance oscillates between zero and high resistance. We have fabricated the Corbino samples with special shape, and have succeeded to measure σ_<xx>Ck up to 100T. A structure corresponding to the 1/3 fractional Hall state was observed about at 80T. Less

这项工作的目的是找到并澄清新的电子相，这些相位出现在100T以上的超高磁场下出现在低维电子系统中。在演讲工作中，我们试图在脉冲超高磁场下测量具有美国宽度的脉冲超高磁场，这是通过电子通量压缩方法或单线线圈直接放电方法生成的。为了克服巨大诱导电压，巨大的排放噪声和由于涡流引起的样品加热的实验难度，我们开发了用于RF传输测量和样品微结合的技术。1。在超高磁场下的电子相关性，用于石墨和二晶的磁场磁铁转移测量结果表明，在高磁场量子限制附近的Shubnikov-De HAAS振荡的位置与与低场振荡的预期相反。这一事实强烈表明，在电子轨道距离高于电子距离的情况下，在高场量子限制下，由于电子相关性而增加的自我纠正。2。超高磁场下的Bloch电子系统准确的指挥NBSE_3显示了双PEIERLS跃迁，一个小的薄电子袋仍处于低温期。我们发现，在所有电子位于最低的Landau水平的高场量子极限中，磁阻单调降低。这种异常行为反映了由于CDW GAP.3的磁故障而导致的最低Landau水平的Harper扩大。超高磁场下的二维电子系统顺序研究了量子厅系统中的高场相，我们已经开发了量子霍尔系统中RF传输测量的技术，其阻抗在零和高电阻之间振荡。我们已经制造了具有特殊形状的Corbino样品，并成功地测量了最高100T的σ_<xx> CK。大约在80T处观察到与1/3分数霍尔状态相对应的结构。较少的