The Effect of Oxygen Adsorption for Vacancy-Induced d0 Magnetism in HfO2 (110) Surface
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Based on the density functional theory, we investigated the electronic structures and magnetic properties of the oxygen adsorption on the defective cubic HfO2 (110) surface. The adsorption capacities of the perfect and defective surfaces follow in the sequence as: oxygen-deficient model >perfect surface >hafnium-deficient model. When the oxygen molecules adsorb on the nonmagnetic perfect HfO2 surface, the system has a local magnetic moment and the antiferromagnetic coupling is more stable. For the defective cubic HfO2 (110) surface, it is found that the oxygen vacancy is more easy to form than the hafnium vacancy by comparing the vacancy formation energy. And the hafnium vacancy could induce a large magnetic moment while the oxygen vacancy alone could not. After adsorption of the oxygen molecule, the nonmagnetic oxygen-deficient HfO2 model is transformed into the magnetic surface. On the contrary, the introduction of adsorbed oxygen molecule causes the magnetic moment of hafnium-deficient HfO2 surface to reduce. Additionally, if the oxygen molecules adsorb on the defective HfO2 (110) surface, the ferromagnetic coupling is energetically favorable.
KeywordsSurface Magnetism First-principle calculations Vacancy Oxygen adsorption
This work was supported by the National Natural Science Foundation of China (Grant No. 11604234, 11404236, and 51602214), Special Funds of the National Natural Science Foundation of China (Grant No. 11447189), and Natural Science Foundation of Shanxi (Grant No. 2015021026 and 201601D202010).