Kan Hongjun, Miao Yuanyuan, Qiu Shuai, Zhang Guangping, Ren Junfeng, Wang Chuankui, Hu Guichao
Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, Jinan 250100, China.
Phys Chem Chem Phys. 2020 Jul 21;22(27):15707-15715. doi: 10.1039/d0cp01872d. Epub 2020 Jul 3.
With a nonadiabatic dynamical method the polaron dynamics in organic ferromagnets with spin radicals is investigated under weak electric fields. The results reveal two novel phenomena different from those in normal polymers due to the existence of spin radicals. One is that the velocity of the polaron is asymmetric upon the reversal of the applied electric field, which is explained from the asymmetric polarity of the polaron charge density in different directions of the field, and hence its effect on the lattice distortion. The other is the 'intermittent rebound' of the polaron, where the polaron intermittently moves against the electric field force during a short interval behaving like a negative current. The details of lattice distortion and charge distribution of the polaron during the process have been revealed. We further found that there exist different critical fields for the above two phenomena. With an increase of the electric field, the 'intermittent rebound' of the polaron vanishes first and subsequently the asymmetric polaron velocity. This work demonstrates the unique properties of polaron transport in organic ferromagnets, and will be helpful in the future design of organic ferromagnetic devices.
采用非绝热动力学方法，研究了在弱电场下含自旋自由基的有机铁磁体中的极化子动力学。结果揭示了由于自旋自由基的存在而出现的两种与普通聚合物不同的新现象。一种是极化子速度在施加电场反转时不对称，这可从极化子电荷密度在电场不同方向上的不对称极性及其对晶格畸变的影响来解释。另一种是极化子的“间歇性反弹”，即极化子在短时间间隔内间歇性地逆着电场力移动，表现得像负电流。该过程中晶格畸变和极化子电荷分布的细节已被揭示。我们还进一步发现上述两种现象存在不同的临界场。随着电场增加，极化子的“间歇性反弹”首先消失，随后不对称极化子速度消失。这项工作展示了有机铁磁体中极化子输运的独特性质，并将有助于未来有机铁磁器件的设计。
