Chemistry Division, Los Alamos National Laboratory, New Mexico 87545, USA.
Phys Rev Lett. 2011 Aug 5;107(6):067402. doi: 10.1103/PhysRevLett.107.067402. Epub 2011 Aug 3.
We report magnetophotoluminescence studies of strongly quantum-confined 0D diluted magnetic semiconductors (DMS), realized in Mn(2+)-doped ZnSe/CdSe core-shell colloidal nanocrystals. In marked contrast to their 3D (bulk), 2D (quantum well), 1D (quantum wire), and 0D (self-assembled quantum dot) DMS counterparts, the ubiquitous yellow emission band from internal d-d ((4)T(1)→(6)A(1)) transitions of the Mn(2+) ions in these nanocrystals is not suppressed in applied magnetic fields and does become circularly polarized. This polarization tracks the Mn(2+) magnetization, and is accompanied by a sizable energy splitting between right- and left-circular emission components that scales with the exciton-Mn sp-d coupling strength (which, in turn, is tunable with nanocrystal size). These data highlight the influence of strong quantum confinement on both the excitation and the emission mechanisms of magnetic ions in DMS nanomaterials.
我们报告了强量子限制的零维稀磁半导体（DMS）的磁光致发光研究，这些 DMS 是在 Mn(2+)掺杂的 ZnSe/CdSe 核壳胶体纳米晶中实现的。与它们的三维（体）、二维（量子阱）、一维（量子线）和零维（自组装量子点）DMS 对应物形成鲜明对比的是，这些纳米晶中 Mn(2+)离子的普遍存在的黄带内 d-d((4)T(1)→(6)A(1))跃迁的光致发光在磁场中没有被抑制，而且变得圆偏振。这种偏振跟踪 Mn(2+)的磁化，并且伴随着右圆和左圆发射分量之间的相当大的能量分裂，该能量分裂与激子-Mn sp-d 耦合强度成正比（反过来，这可以通过纳米晶尺寸进行调节）。这些数据突出了强量子限制对 DMS 纳米材料中磁性离子的激发和发射机制的影响。
