Spin-orbit coupling induced demagnetization in Ni: Ab initio nonadiabatic molecular dynamics perspective

Enhanced Electron Transfer and Spin Flip through Spin–Orbital Couplings in Organic/Inorganic Heterojunctions: A Nonadiabatic Surface Hopping Simulation

“…Consequently, the fundamental knowledge of the fate of electron spin during the interlayer charge transfer and relaxation in solids, which is important for light harvesting, efficiency promotion of organic solar cells, and applicable high-IQE luminescent devices, , continues to be a missing piece of information because of the absence of suitable theoretical tools. ,, Therefore, there is an urgent need to investigate SOC-induced spin-related electron dynamics at organic/inorganic interfaces. Recently, Zheng et al . introduced SOC-induced spin dynamics into the TDKS-based NA-MD via spin-diabatic and spin-adiabatic representations, where SOCs open new transition channels between KS orbitals with different spin components.…”

“…Therefore, ZnPc/MoS 2 is chosen as a prototypical system in this Letter, reporting a fast spin flip process and an enhanced dynamical channel for electron transfer and relaxation resulting from the strong SOCs of the MoS 2 component. Utilizing the latest experimental works and theoretical approaches, we study the ZnPc/MoS 2 heterojunction spin flip mechanism upon ZnPc photoexcitation through TDKS-based NA-MD simulations with the inclusion of SOC-induced spin dynamics via the Hefei-NAMD code (Hefei-NAMD_SOC version) , at the density functional theory (DFT) level. − First, this Letter reveals that SOCs permit “expanding” nonadiabatic couplings (NACs), thus providing a new transferring route where the electron transition occurs directly between the lowest unoccupied molecular orbital (LUMO) of ZnPc and the conduction band minimum (CBM) of MoS 2 (briefly, the direct channel), which is different from the normal channel where the transferring occurs sequentially (LUMO–high CB–CBM). The direct and normal channels exhibit competitive relationships, proved by the frequency analysis and decrease of NACs after the broadening.…”

“…The spin-diabatic representation utilizes the spin-polarized Kohn–Sham (KS) orbitals where SOCs are ignored in eigenstates and eigenvalues; therefore, the total electronic Hamiltonian consists of eigenvalues in a diagonal as well as EPCs and SOCs in nondiagonal regions between different KS orbitals. On the other hand, the spin-adiabatic representation relies on spinor basis sets and further diagonalizes the total Hamiltonian mentioned above, for which SOCs are considered in the potential energy surfaces (PESs) . Spin-adiabatic and spin-diabatic representations are different methods to consider SOCs in NA-MD simulations; nevertheless, they can complement each other under some circumstances.…”

“…Theoretically, the spin-adiabatic representation is more accurate and suitable for most systems, while the spin-diabatic representation is appealing if SOCs are relatively weak. − On the other hand, although the spin-adiabatic representation is more widely applicable, the spin-diabatic representation has an advantage in drawing a distinction between the contributions from EPCs and SOCs. In fact, in actual applications, the two representations can achieve accurate enough descriptions of the spin flip process in principle. , The detailed discussion of spin-diabatic and spin-adiabatic representations can be found in reviews by Zheng et al ., Mukherjee et al ., and Granucci et al . Hence, considering the pros and cons of spin-adiabatic and spin-diabatic representations, we utilize the two representations to study the spin flip process, where the spin-adiabatic representation is chosen to simulate the electron dynamical behaviors, while the spin-diabatic representation provides the analysis of EPCs and SOCs.…”

“…30,31,46 Therefore, there is an urgent need to investigate SOC-induced spin-related electron dynamics at organic/ inorganic interfaces. Recently, Zheng et al 61 introduced SOC-induced spin dynamics into the TDKS-based NA-MD via spin-diabatic and spin-adiabatic representations, where SOCs open new transition channels between KS orbitals with different spin components. Two representations were used to investigate the ultrafast demagnetization in face-centered cubic (FCC) bulk Ni, hence depicting distinct relaxation pathways driven by EPCs and SOCs that complemented the timeresolved diffraction results.…”