Htoon H, Crooker S A, Furis M, Jeong S, Efros Al L, Klimov V I
Chemistry Division and the Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Phys Rev Lett. 2009 Jan 9;102(1):017402. doi: 10.1103/PhysRevLett.102.017402.
We study the low-temperature magnetophotoluminescence from individual CdSe nanocrystals. Nanocrystals having a small "bright" exciton fine structure splitting (Delta_{XY}<0.5 meV) exhibit a conventional left and right circularly polarized Zeeman photoluminescence doublet in applied magnetic fields. In contrast, nanocrystals with large Delta_{XY} (>1 meV) show an anomalous magnetophotoluminescence polarization, wherein the lower-energy peak becomes circularly polarized with increasing field, while the higher-energy peak remains linearly polarized. This unusual behavior arises from strong mixing between the absorbing and emitting bright exciton levels due to strong anisotropic exchange interactions.
我们研究了单个CdSe纳米晶体的低温磁光致发光。具有小的“明亮”激子精细结构分裂（ΔXY<0.5 meV）的纳米晶体在施加磁场时表现出传统的左旋和右旋圆偏振塞曼光致发光双峰。相比之下，具有大的ΔXY（>1 meV）的纳米晶体表现出异常的磁光致发光极化，其中随着磁场增加，低能峰变为圆偏振，而高能峰保持线性偏振。这种不寻常的行为源于由于强各向异性交换相互作用导致的吸收和发射明亮激子能级之间的强混合。
