The effect of annealing temperature on the magnetic anisotropy in Co ultrathin film on MgO(001) substrate
Yong-Sheng Zhang,
Wei He,
Jin Tang,
Syed Sheraz Ahmad,
Wei Zhang,
Yan Li,
Xiang-Qun Zhang,
Zhao-Hua Cheng
Affiliations
Yong-Sheng Zhang
State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Wei He
State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Jin Tang
State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Syed Sheraz Ahmad
State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Wei Zhang
State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Yan Li
State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Xiang-Qun Zhang
State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Zhao-Hua Cheng
State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Co epitaxial thin films with 2.5nm thickness were prepared on single-crystal MgO(001) substrates and annealed at different temperatures. The contribution of each interface of the MgO/Co/Cu trilayer to the in-plane magnetic anisotropy (IMA) was studied by changing interfacial coupling through annealing. The structure was measured by low energy electron diffraction (LEED), and the magnetic properties were measured using the anisotropic magnetoresistance (AMR) measurements and the longitudinal Magneto-optical Kerr effect magnetometer (MOKE). We found that the magnetic anisotropy of the as-deposited one shows superposition of a two-fold symmetry with a weak four-fold contribution caused by the stress of the interface between Co/Cu, which is along the easy axis [-110]. After annealing at 200°C, the symmetry of magnetic anisotropy was changed from uniaxial magnetic anisotropy (UMA) into four-fold symmetry due to the significant increasing of four-fold magnetocrystalline anisotropy. When the films were annealed above 300°C, the damage of the MgO/Co interface additionally decreased the IMA to isotropy. Meanwhile, the coercivity raised from 45Oe (without annealing) to 1200Oe (annealed at 400°C) along the easy axis direction. Our experimental results prove that the Co/Cu interface and the MgO/Co interface play an essential role in manipulating the four-fold and the UMA in the system.
