Wang Hui, Li Yuan, Li Dong-Mei, Cui Bin, Liu De-Sheng
School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China.
Phys Chem Chem Phys. 2016 Jan 7;18(1):503-9. doi: 10.1039/c5cp05789b. Epub 2015 Nov 30.
We present a model study of the dynamic properties of a polaron in an organic ferromagnetic polymer by focusing on the spin correlation between the polymer backbone and the side radicals. The simulations are performed by using a tight-binding description coupled with a nonadiabatic dynamics method. We find that, in the presence of an external electric field, the polarons with both up and down spins can get trapped near the side radicals of the polymer chain unless the electric field is stronger than a critical field. However, the magnitudes of the critical electric field vary quite differently for the spin-up and spin-down polarons as a function of the number of side radicals in the polymer, leading to the exponential change of the range of the electric field within which the spin-filtering takes place. The range of the electric field increases nearly in a linear manner with the strength of the electron-lattice coupling as a result of the increase of the polaron binding energy. The impact of the strength of the spin correlation between the backbone and the side radicals on the polaron spin filtering is also discussed. These findings are expected to be useful for the design of organic-based spin filters.
我们通过关注聚合物主链与侧基自由基之间的自旋相关性，对有机铁磁聚合物中极化子的动力学性质进行了模型研究。模拟采用紧束缚描述与非绝热动力学方法相结合的方式进行。我们发现，在存在外部电场的情况下，除非电场强度超过临界场，否则具有上自旋和下自旋的极化子都会被困在聚合物链的侧基附近。然而，作为聚合物中侧基数量的函数，上自旋和下自旋极化子的临界电场大小变化差异很大，导致发生自旋过滤的电场范围呈指数变化。由于极化子结合能的增加，电场范围几乎随电子 - 晶格耦合强度呈线性增加。还讨论了主链与侧基自由基之间自旋相关性强度对极化子自旋过滤的影响。这些发现有望对基于有机材料的自旋过滤器设计有所帮助。
