Quantum dots due to the flux line lattice in the hybrid structure of diluted magnetic semiconductors and superconductors and its application

在第二类超导体的混合态中，由于磁通的规则分布，磁通密度在表面发生了空间调制。在第二类超导体表面附着稀磁半导体的混合结构中，期望稀磁半导体的有效带隙受到上述场调制的调制，零维量子限制是通过超导体中的磁通线晶格来实现的。在本研究项目中，我们尝试用分子束外延技术制备了Cd_1-x&Gt；Mn_xTe和NbSe_2的混杂结构，NbSe_2具有层状晶体结构，其中层与层之间的耦合是由于范德华力的作用。闪锌矿晶体结构的外延生长在层状晶体上属于准范德华外延的范畴，即层状晶体的表面没有悬挂的bo…。更多的NDS，预计即使在33%的失配情况下，闪锌矿晶体也可以在没有界面应变的情况下生长。在RHEED图像的原位观察中，NbSe_2的条纹图案连续地转变为CdTe(111)表面的条纹图案，这表明在生长的最初阶段就实现了二维生长。为了研究NbSe_2中磁通对磁场调制的影响，我们对NbSe_2上生长的Cd_&lt；1-x&gt；Mn_xTe薄膜和Cd_&lt；1-x&gt；Mn_xTe/Cd_&lt；1-y&gt；Mn_yTe单量子阱(SQW)进行了磁致发光测量。在4.2K以下的低温下，激子发射的线宽表现出反常的行为；线宽随磁场的增大先增大后最大，随磁场的进一步增大而减小。这种反常行为可以理解为磁通线晶格引起的场调制效应。较少

In the mixed state of type-II superconductors, the spatial modulation of magnetic flux density takes place on the surface due to the regular distribution of magnetic flux. In the hybrid structure in which diluted magnetic semiconductors (DMS) are attached on the surface of type-II superconductors, it is expected that the effective band-gap of DMS is modulated by the above field modulation and quantum confinement in the zero-dimension is realized by the flux line lattice in the superconductors. In the present research project, we have tried to fabricate the hybrid structure of Cd_<1-x> Mn_xTe and NbSe_2 by MBE growth technique.NbSe_2 is of the layered crystal structure, in which the coupling between the layers is due to van der Waals force. The epitaxial growth of the zinc-blende crystal structure, CdTe or Cd_<1-x> Mn_xTe in the present case, on the layered crystal belongs to the category of quasi-van der Waals epitaxy ; that is, the surface of the layered crystal is free of dangling bo … More nds, onto which it is expected the zincblende crystal is grown without interface strain even with a mismatch of 33%. In in situ observation of the RHEED image, the streak pattern of NbSe_2 was transformed into that of CdTe(111) surface continuously, which showed that the two-dimensional growth was achieved at the very initial stage of the growth. Photoluminescence (PL) measurements of the grown crystals showed a good optical quality with a narrow linewidth of the exciton emission.In order to examine the effect of the magnetic field modulation due to the magnetic flux in NbSe_2, we have performed magneto-PL measurements on Cd_<1-x>Mn_xTe films and Cd_<1-x>Mn_xTe/Cd_<1-y> Mn_yTe single quantum well (SQW) grown on NbSe_2. At low temperatures less than 4.2K, the linewidth of the excitonic emission showed anomalous behaviors ; that is, the linewidth first increased with magnetic fields, then took maximum, and decreased with the further increase of magnetic fields. This anomalous behavior could be understood as the effect of the field modulation due to the flux line lattice. Less