The Theoretical Study Of Organic Small Molecules/Fe₄N(La_2/3Sr_1/3MnO₃) Spinterfaces

The development of organic spintronic devices are promoted by the novel interfaces between magnetic and organic materials.The isolate organic molecule,such as C6H6,can act as the spin filter at such interfaces.As organic molecules adsorbed on the forremagnets,like Fe,Co,Mn etc,the spatial spin polarization inversion can be realized.Meanwhile,the inversion induced by organic molecular adsorptions is quite useful for controlling the spin injection.However,the details of spinterfaces between compound ferromagnets and organic molecules are not clear.Fe4 N and La2/3Sr1/3MnO3 are typically high spin-polarized materials with high Curie temperatures of 761 and 370 K respectively.Their prominent properties improve their practicability,especially as the electrode materials.We study the spinterfaces between the small organic molecules and compound ferromagnets(Fe4N and La2/3Sr1/3MnO3)which are based on density-functional theory,and analyze adsorptions energy,spatial spin polarization,magnetic and electronic structures of the adsorptions.The study provides the basis for spintronic devices design,especially their spatial spin polarization injection and inversion.When the Fe4 N substrate is modeled by three atomic layers,the four adsorptions models fall into two categories: the endothermic adsorptions(two FeIIN terminal models)and the exothermic adsorptions(two FeIFeII terminal models).The spatial spin polarization inversion happens in FeIIN-C models;C6H6 does not form bonds with Fe4 N in FeIIN-NC model;FeIFeII-C has the spatial spin polarization inversion at the interface;and the spatial spin polarization inversion originates from the positive spin polarization of N atoms in FeIFeII-NC model.The inversion in FeIIN-C and FeIFeII-C finds its origin in the strong p-d hybridizations.In the C5H5/Fe4 N models,the spatial spin polarization inversion happens due to the hybridizations between C p and Fe d orbitals,while in the SC4H4/Fe4 N model,the inversion is weak.The moment inversion of two Fe atoms under the C6H6 happens when the number of Fe4 N atomic layers is more than or equal to five,which leads to the antiferromagnetic order at the first Fe4 N atomic layer.The spatial spin polarization inversion at C6H6 center can extend into the vacuum layer deeply.For La2/3Sr1/3MnO3 adsorptions,the ordered models and disordered models are considered in our calculations.For ordered models,the adsorptions density of C6H6 is also considered.Adsorptions with different terminations are the exothermic adsorptions,and the LaO terminations keep larger adsorptions energy than other models.Strong spin injection happens in MnAO and MnBO terminations.The spatial spin polarization injection happens in C6H6 layer,which is independent of terminations.It is different from the organic molecular adsorptions based on Fe4 N.