Erdin Serkan, van Veenendaal Michel
Department of Physics, Northern Illinois University, DeKalb, Illinois 60115, USA.
Phys Rev Lett. 2006 Dec 15;97(24):247202. doi: 10.1103/PhysRevLett.97.247202. Epub 2006 Dec 11.
The photoinduced magnetism in Mn-tetracyanoethylene (TCNE) molecule-based magnets is ascribed to charge-transfer excitations from manganese to TCNE. Charge-transfer energies are calculated using density functional theory; photoinduced magnetization is described using a model Hamiltonian based on a double-exchange mechanism. Photoexciting electrons from the manganese core spins into the lowest unoccupied orbital of TCNE with photon energies around 3 eV increase the magnetization through a reduction of the canting angle of the manganese core spins for an average electron density on TCNE less than one. When photoexciting with a smaller energy, divalent TCNE molecules are formed. The delocalization of the excited electron causes a local spin flip of a manganese core spin.
基于锰-四氰基乙烯（TCNE）分子磁体中的光致磁性归因于从锰到TCNE的电荷转移激发。利用密度泛函理论计算电荷转移能；基于双交换机制，使用模型哈密顿量描述光致磁化。当光子能量约为3 eV时，光激发锰核自旋中的电子进入TCNE的最低未占据轨道，对于TCNE上平均电子密度小于1的情况，通过减小锰核自旋的倾斜角来增加磁化强度。当用较小能量进行光激发时，会形成二价TCNE分子。激发电子的离域导致锰核自旋的局部自旋翻转。
