Tailoring the topology of an artificial magnetic skyrmion

栗佳 博士后

Dept. of Physics, University of California at Berkeley, 美国

颜世申 教授

2015-04-16 10:00

知新楼C702 量子报告厅

A skyrmion is a topological twist of a continuous field that was first proposed by Skyrme to describe discrete nucleons. In condensed-matter physics, skyrmions emerge as topological invariant spin textures in a two dimensional Heisenberg spin lattice. Evidence of skyrmions in condensed matter physics appeared after the discovery of the Quantum Hall Effect in which the lowest energy charged excitations can be mapped onto two-dimensional magnetic skyrmion states. Despite theoretical predictions, it remains an experimental challenge to realize an artificial magnetic skyrmion whose topology can be well controlled and tailored so that its topological effect can be revealed explicitly in a deformation of the spin textures. Here we report epitaxial magnetic thin films in which an artificial skyrmion is created by embedding a magnetic vortex into an out-of-plane aligned spin environment. By changing the relative orientation between the central vortex core polarity and the surrounding out-of-plane spins, we are able to control and tailor the system between two skyrmion topological states. An in-plane magnetic field is used to annihilate the skyrmion core by converting the central vortex state into a single domain state. Our result shows distinct annihilation behaviour of the skyrmion core for the two different skyrmion states, suggesting a topological effect of the magnetic skyrmions in the core annihilation process.

Postdoc, University of California at Berkeley, Sept. 2010-present

Ph. D. in Physics, Sept. 2005-2010, Fudan

B.S. in Material Science, Sept. 2001-2005

发表文章目录：

1. Chirality switching and winding/unwinding of the antiferromagnetic NiO domain walls in Fe/NiO/Fe/CoO/Ag(001), J. Li, A. Tan, S. Ma, R. F. Yang, E. Arenholz, C. Hwang, and Z. Q. Qiu, Phys. Rev. Lett. 113, 147207 (2014)

2. Tailoring the topology of an artificial magnetic skyrmion, J. Li, A. Tan, K. W. Moon, A. Doran, M. A. Marcus, A. T. Young, E. Arenholz, S., Ma, R. F. Yang, C. Hwang, and Z. Q. Qiu, Nature Communications 5, 4704 (2014)

3. Stabilizing a magnetic vortex/antivortex array in single crystalline Fe/Ag(001) microstructures, J. Li, A. Tan, K. W. Moon, A. Doran, M. A. Marcus, A. T. Young, E. Arenholz, S. Ma, R. F. Yang, C. Hwang, and Z. Q. Qiu, Appl. Phys. Lett. 104, 262409 (2014)

4. Imprinting antivortex states from ferromagnetic Fe into antiferromagnetic NiO in epitaxial NiO/Fe/Ag(001) microstructures, J. Li, A. Tan, K. W. Moon, A. Doran, M. A. Marcus, A. T. Young, E. Arenholz, S. Ma, R. F. Yang, C. Hwang, and Z. Q. Qiu, Appl. Phys. Lett. 104, 112407 (2014)

5. Novel Chiral Magnetic DomainWall Structure in Fe/Ni/Cu(001) Films, G. Chen, J. Zhu, A. Quesada, J. Li, A. T. N'Diaye, Y. Huo, T.P. Ma, Y. Chen, H.Y. Kwon, C. Won, Z.Q. Qiu, A.K. Schmid, and Y. Z. Wu, Phys. Rev. Lett. 110, 177204 (2013)

6. Magnetic anisotropy in epitaxial Py/FeMn/Cu(001) and Py/FeMn/Ni/Cu(001) films, A. Tan, J. Li, C. A. Jenkins, E. Arenholz, A. Scholl, C. Hwang, and Z. Q. Qiu, Phys. Rev. B 88, 104404 (2013)

7. Measurement of the spectral line shapes for orbital excitations in the Mott insulator CoO using high-resolution resonant inelastic x-ray scattering, L. Andrew Wray, J. Li, Z. Q. Qiu, Jinsheng Wen, Zhijun Xu, GendaGu, Shih-Wen Huang, Elke Arenholz, Wanli Yang, Zahid Hussain, and Yi-De Chua, Phys. Rev. B 88, 035105 (2013)

8. Magnetic dead layer at the interface between a Co film and the topological insulator Bi2Se3 J. Li, Z. Y. Wang, A. Tan, P.-A. Glans, E. Arenholz, C. Hwang, J. Shi, and Z. Q.Qiu, Phys. Rev. B 86, 054430 (2012)

9. Design of a vector magnet for the measurements of anisotropic magnetoresistance and rotational magneto-optic Kerr effect, J. Li, E. Jin, H. Son, A. Tan, W. N. Cao, Chanyong Hwang, and Z. Q. Qiu, Review of Scientific Instruments, 83, 033906 (2012)

10. Exchange bias in epitaxially grown CoO/MgO/Fe/Ag(001), A. Tan, J. Li, C. A. Jenkins, E. Arenholz, A. Scholl, C. Hwang, and Z. Q. Qiu, Phys. Rev. B 86, 064406 (2012)

11. Magnetic interlayer coupling between antiferromagnetic CoO and ferromagnetic Fe across a Ag spacer layer in epitaxially grown CoO/Ag/Fe/Ag(001), Y. Meng, J. Li, P.-A. Glans, C. A. Jenkins, E. Arenholz, A. Tan, J. Gibbons, J. S.Park, Chanyong Hwang, H. W. Zhao, and Z. Q. Qiu, Phys. Rev. B 85, 014425 (2012)

12. NiO-thickness dependent magnetic anisotropies in Fe/NiO/Au(001) and Fe/NiO/MgO(001) systems, L.Y. Ma, G. Chen, J. Li, J. Zhu, Z.Q.Qiu and Y.Z. Wu, J. Magn. Magn.Mater. 324, 528 (2012)

13. Determination of the Fe magnetic anisotropies and the CoO frozen spins in epitaxial CoO/Fe/Ag(001), J. Li, Y. Meng, J. S. Park, C.A. Jenkins, E. Arenholz, A. Scholl, A. Tan, H. Son, H. W. Zhao, Chanyong Hwang, Y. Z. Wu, and Z. Q. Qiu, Phys. Rev. B 84, 094447 (2011)

14. Continuous Spin Reorientation Transition in Epitaxial Antiferromagnetic NiO Thin Films, J. Li, E. Arenholz, Y. Meng, A. Tan, J. Park, E. Jin, H. Son, J. Wu, C.A. Jenkins, A. Scholl, H. W. Zhao, Chanyong Hwang, and Z. Q. Qiu, Phys. Rev. B 84, 012406 (2011)

15. In-plane spin reorientation transition in Fe/NiO bilayers on Ag(1,1,10), J. Li, M. Przybylski, F. Yildiz, X.L. Fu, and Y. Z. Wu, Phys. Rev. B, 83, 094436 (2011)

16. Quantum Well States and Oscillatory Magnetic Anisotropy in Ultrathin Fe Films, J. Li, G. Chen, M. Przybylski, E. Rotenberg, and Y. Z. Wu, IEEE Tran. Magn. 47, 1603 (2011)

17. A study of FeMn/Fe/Co/Cu(1,1,10) films using MOKE and XMCD, Y. Meng, J. Li, A. Tan, J. Park, E. Jin, H. Son, A. Doran, A. Scholl, E. Arenholz, H. W. Zhao, Chanyong Hwang, and Z. Q. Qiu, Phys. Rev. B 84, 064416 (2011)

18. Element-specific study of epitaxial NiO/Ag/CoO/Fe films grown on vicinal Ag(001) using Photoemission Electron Microscopy, Y. Meng, J. Li, A. Tan, E. Jin, J. Son, J. S. Park, A. Doran, A.T. Young, A. Scholl, E. Arenholz, J. Wu, C. Hwang, H. W. Zhao, and Z. Q. Qiu, Appl. Phys. Lett. 98, 212508 (2011)

19. Determination of spin-polarized quantum well states and spin-split energy dispersions of Co ultrathin films grown on Mo(110), J. S. Park, A. Quesada, Y. Meng, J. Li, E. Jin, H. Son, A. Tan, J. Wu, C. Hwang, H. W. Zhao, A. K. Schmid, and Z. Q. Qiu, Phys. Rev. B 83, 113405 (2011)

20. Temperature-dependent magnetic anisotropies in epitaxial Fe/CoO/MgO(001) system studied by the planar Hall effect, W. N. Cao, J. Li, G. Chen, J. Zhu, C.R. Hu, and Y. Z. Wu, Appl. Phys. Lett.98, 262506 (2011)

21. Revealing the volume magnetic anisotropy of Fe films epitaxied on GaAs (001) surface, G. Chen, J. Zhu, J. Li, F. Z. Liu, and Y. Z. Wu, Appl. Phys. Lett. 98, 132505 (2011)

22. Experimental observation of quantum oscillations of perpendicular anisotropy Fe films on Ag(1,1,10) , J. Li,M. Przybylski, Y. He, and Y. Z. Wu, Phys. Rev. B, 82, 214406 (2010)

23. Four-fold magnetic anisotropy induced by the antiferromagnetic order in FeMn/Co/Cu(001) system, G. Chen, J. Li, F. Z. Liu, J. Zhu, Y. He, J. Wu, Z. Q. Qiu, and Y. Z. Wu, J. Appl. Phys. 108, 073905 (2010)

24. Oscillatory Magnetic Anisotropy Originating from QuantumWell States in Fe Films, J. Li, M. Przybylski, F. Yildiz, X. D. Ma, and Y. Z. Wu, Phys. Rev. Lett. 102, 207206 (2009)