关键词: 第一性原理/
Co/h-BN/
Dzyaloshinsky-Moriya相互作用/
斯格明子
English Abstract
First principle study of weak Dzyaloshinsky-Moriya interaction in Co/BN surface
Huang Can1,Li Xiao-Ying1,
Zhu Yan1,
Pan Yan-Fei1,
Fan Ji-Yu1,
Shi Da-Ning1,
Ma Chun-Lan2
1.College of Science, Nanjing University of Aeronautics and Astronautics, Najing 210006, China;
2.School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos. 11204131, 11374159), the Natural Science Foundation of Jiangsu Higher Education Institutions, China (Grant No. 17KJA140001), and the Six Talent Peaks Project of Jiangsu, China (Grant No. XCL-078).Received Date:20 February 2018
Accepted Date:18 March 2018
Published Online:05 June 2018
Abstract:Based on density functional theory calculations, we elucidate the atomic and electronic structures of Co atom of hexgonal BN (Co/h-BN). The interaction between magnetic moments of Co atoms is realized through Co-N_-B_ grid, which is indicated by the analysis of spin charge contour plot and partial density of states of each atom, where and denote the site of B or N atom close to and away from Co atom, respectively. Then the dispersion relations E(q) and E(-q) (q denotes the direction vector of spin spiral) between energy and wave vector of spin spiral in the opposite directions are calculated with generalized Bloch equations. In the incommensurate spin spiral calculations, all the magnetic moments of Co atom are arranged in the same plane that is perpendicular to the Co/h-BN film. The difference between E(q) and E(-q) is caused by the interface of Co/h-BN, where the symmetry of space perpendicular to the film is broken. Moreover, the effective Heisenberg exchange interaction (HBI) and Dzyaloshinsky-Moriya interaction (DMI) parameters between different neighbors (Ji and di) are derived by well fitting the ab initio magnon dispersion E(q) to HBI with DMI model and E(q)-E(-q) to DMI model, respectively. The J1 has a negative value and plays a major role, J3 is one order of magnitude smaller than J1, and other parameters are close to zero. Hence, Co/h-BN is triangular antiferromagnetic material with the q at k point in the first Brillouin zone. However, the spin spiral with the q at M point is only 2 meV larger than the basic state with the only negative J1 and smaller positive J2. The DMI is not shown in this interface with d1 and d2 close to zero. Based on the non DMI character and its stability in air, h-BN can be capped on other DMI interfaces. The reason that the DMI in Co/h-BN is much smaller than in Co/Gra is much larger height between Co and h-BN. It is 0.192 nm for h-BN but it is 0.156 nm for Co/Gra. We may reduce the height to enhance the DMI by other ways, such as adding electrical and magnetic fields in the future.
Keywords: first principles/
Co/h-BN/
Dzyaloshinsky-Moriya interaction/
Skyrmion
