Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan.
J Phys Condens Matter. 2012 Aug 15;24(32):325801, 1-6. doi: 10.1088/0953-8984/24/32/325801. Epub 2012 Jul 12.
In Cd(0.8)Mn(0.2)Te, nonlinear photoluminescence (PL) appears only when localized excitons are selectively excited to high-density states. Here, the effect of a magnetic field is compared between nonlinear PL and PL due to localized magnetic polarons. Nonlinear PL shows a shift towards lower energy under an applied magnetic field, whereas PL of a localized magnetic polaron band shows a slight shift towards higher energy. The experimental results support the hypothesis that the origin of the nonlinear PL is a spin-aligned state of high-density exciton magnetic polarons. In the spin-aligned state, most spins of electrons (holes) in many magnetic polarons point in the same direction. In this new high-density photoexcited state, the s, p-d exchange interaction between photoexcited electrons (holes) and magnetic ions plays an important role.
在 Cd(0.8)Mn(0.2)Te 中，只有当局域激子被选择性地激发到高密度态时，才会出现非线性光致发光 (PL)。在这里，比较了磁场对非线性 PL 和局域磁极化子 PL 的影响。在施加磁场的情况下，非线性 PL 向低能量移动，而局域磁极化子带的 PL 则略微向高能量移动。实验结果支持了这样的假设，即非线性 PL 的起源是高密度激子磁极化子的自旋对齐态。在自旋对齐态中，许多磁极化子中的电子（空穴）的大多数自旋指向相同的方向。在这个新的高密度光激发态中，光激发电子（空穴）和磁性离子之间的 s、p-d 交换相互作用起着重要作用。
