Magnetic resonance in semiconductors

在第二个资助期内，我们将继续进行电子自旋共振（ESR）研究，旨在了解III/V半导体和半导体异质结构（如GaAs）中的长寿命自旋相干电子态。沿着使用先进但传统的ESR技术的基础上直接检测的吸收微波辐射的谐振，我们也将集中在电检测ESR（EDMR）计划与光泵浦的可能性。这种方法将产生一个强烈的增加的灵敏度，这是特别重要的研究与小自旋浓度的异质结构。传统的ESR和EDMR技术的组合将使互补的见解自旋退相和自旋弛豫过程，特别是关于光激发的自旋极化电子和施主态，杂质和位错之间的相互作用。载流子浓度对自旋相干性的影响将通过研究具有不同化学掺杂的样品组来检查，但也可以在电子浓度由栅极电压控制的异质结构中检查。最后，石墨烯的自旋性质也将通过ESR和EDMR来解决。在这里，实验将集中在理解一个非常特殊的电子结构和主导的自旋-自旋相互作用和石墨烯中电子的弛豫路径之间的关系。

In the second funding period we will continue electron spin resonance (ESR) studies aimed at the understanding of the long-living spin coherent electron states in III/V semiconductors and semiconductor heterostructures, such as GaAs. Along with using advanced but yet traditional ESR techniques based on the direct detection of the absorbed microwave radiation at the resonance, we will also focus on the electrically detected ESR (EDMR) schemes with the possibility of optical pumping. This approach will yield a strong increase of the sensitivity which is particularly important for studies of heterostuructures with small spin concentration. A combination of conventional ESR and EDMR techniques will enable complementary insights into the spin-dephasing and spin relaxation processes in particular regarding the interplay between optically excited spin-polarized electrons and donor states, impurities and dislocations. The influence of the carrier concentration on the spin coherence will be examined by studying sets of samples with different chemical doping but also in heterostructures where the electron concentration is controlled by the gate voltage. Finally, the spin properties of graphene will also be addressed by ESR and EDMR. Here the experiments will focus on the understanding of the relation between a very peculiar electronic structure and the dominant spin-spin interactions and relaxation paths of electrons in graphene.