van Schooten Kipp J, Baird Douglas L, Limes Mark E, Lupton John M, Boehme Christoph
Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, Utah 84112-0830, USA.
1] Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, Utah 84112-0830, USA [2] Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
Nat Commun. 2015 Apr 14;6:6688. doi: 10.1038/ncomms7688.
Weakly coupled electron spin pairs that experience weak spin-orbit interaction can control electronic transitions in molecular and solid-state systems. Known to determine radical pair reactions, they have been invoked to explain phenomena ranging from avian magnetoreception to spin-dependent charge-carrier recombination and transport. Spin pairs exhibit persistent spin coherence, allowing minute magnetic fields to perturb spin precession and thus recombination rates and photoreaction yields, giving rise to a range of magneto-optoelectronic effects in devices. Little is known, however, about interparticle magnetic interactions within such pairs. Here we present pulsed electrically detected electron spin resonance experiments on poly(styrene-sulfonate)-doped poly(3,4-ethylenedioxythiophene) (
PSS) devices, which show how interparticle spin-spin interactions (magnetic-dipolar and spin-exchange) between charge-carrier spin pairs can be probed through the detuning of spin-Rabi oscillations. The deviation from uncoupled precession frequencies quantifies both the exchange (<30 neV) and dipolar (23.5±1.5 neV) interaction energies responsible for the pair's zero-field splitting, implying quantum mechanical entanglement of charge-carrier spins over distances of 2.1±0.1 nm.
经历弱自旋 - 轨道相互作用的弱耦合电子自旋对可以控制分子和固态系统中的电子跃迁。已知其能决定自由基对反应，人们已用它来解释从鸟类磁感受、自旋相关的电荷载流子复合及输运等一系列现象。自旋对表现出持久的自旋相干性，使得微小磁场能够扰动自旋进动，进而影响复合率和光反应产率，在器件中产生一系列磁光电子效应。然而，对于此类自旋对中粒子间的磁相互作用却知之甚少。在此，我们对聚（苯乙烯磺酸盐）掺杂的聚（3,4 - 亚乙基二氧噻吩）（PEDOT:PSS）器件进行了脉冲电检测电子自旋共振实验，该实验展示了如何通过自旋拉比振荡的失谐来探测电荷载流子自旋对之间的粒子间自旋 - 自旋相互作用（磁偶极和自旋交换）。与未耦合进动频率的偏差量化了导致该对零场分裂的交换相互作用能（<30 neV）和偶极相互作用能（23.5±1.5 neV），这意味着电荷载流子自旋在2.1±0.1 nm的距离上存在量子力学纠缠。
