Ruiz-Díaz P, Núñez-Valencia C, Muñoz-Navia M, Urrutia-Bañuelos E, Dorantes-Dávila J
Instituto de Física, Universidad Autónoma de San Luis Potosí, 78000 San Luis Potosí, México.
Universidad de La Ciénega del Estado de Michoacán de Ocampo, Col. Lomas de la Universidad, Avenida Universidad 3000, Sahuayo, Michoacán, México.
Phys Chem Chem Phys. 2022 Apr 20;24(16):9576-9588. doi: 10.1039/d2cp00482h.
In the framework of first-principles calculations, we comprehensively investigate the external electric-field (EF) manipulation of the magnetic anisotropy energy (MAE) of alloyed CoPt dimers deposited on graphene. In particular, we focus on the possibility of tuning the MAE barriers under the action of external EFs and on the effects of Co-substitution. Among the various considered structures, the lowest-energy configurations were the and , having the Co-atom closest to the graphene layer. The optimal and higher energy configurations were related to the electronic structure through the local density of states and hybridizations between the transition-metal (TM) atoms of the dimer and graphene. In contrast to Co/graphene [M. Tanveer, J. Dorantes-Dávila and G. M. Pastor, , 2017, (22), 224413.], the CoPt dimer having the ground-state configuration, exhibits a much lower value of the MAE (about |Δ| ≃ 4.5 meV per atom) and the direction of the magnetization lies in the graphene layer. Moreover, we observe a spin-reorientation transition occurring at ≃ 0.5 V Å, which opens the possibility of inducing magnetization switching by external electric fields. The microscopic origin of the changes of the MAE associated with changes in the EF has been qualitatively related to the details of the electronic structure by analyzing the local density of states and to the spin-dependent electronic densities close to the Fermi energy. Finally, the role of local environment was quantified by performing electronic structure and magnetic calculations on several higher-energy structure configurations.
在第一性原理计算的框架下，我们全面研究了沉积在石墨烯上的合金化CoPt二聚体的磁各向异性能（MAE）的外电场（EF）调控。特别地，我们关注在外加电场作用下调整MAE势垒的可能性以及Co替代的影响。在各种考虑的结构中，能量最低的构型是 和 ，其中Co原子最靠近石墨烯层。最优和较高能量的构型通过态密度以及二聚体的过渡金属（TM）原子与石墨烯之间的杂化与电子结构相关。与Co/石墨烯[M. Tanveer, J. Dorantes-Dávila和G. M. Pastor, , 2017, (22), 224413.]相比，具有 基态构型的CoPt二聚体表现出低得多的MAE值（每个原子约|Δ|≃4.5 meV），并且磁化方向位于石墨烯层中。此外，我们观察到在 ≃ 0.5 V Å时发生自旋重取向转变，这开启了通过外电场诱导磁化切换的可能性。通过分析态密度以及靠近费米能的自旋相关电子密度，与EF变化相关的MAE变化的微观起源已在定性上与电子结构的细节相关。最后，通过对几种较高能量结构构型进行电子结构和磁性计算，量化了局部环境的作用。
