Topic: A study of artificial magnetic skyrmions

Speaker: Professor Ziqiang Qiu (邱子强 教授)

　　          Department of Physics University of California at Berkeley

Time: 15:30 (Fri.) June 9^th, 2017

Venue: Room 468，Lee Hsun Building, IMR CAS

Abstract

A magnetic skyrmion is a topological twist of two-dimensional spin texture which exhibits many fascinating properties.  In experiment, magnetic skyrmions were recently realized in 2009 in several experimental systems as a result of Dzyaloshinsky-Moriya interactions (DMI). An alternative approach is to produce non-collinear spins in magnetic vortex states.  With this motivation, we fabricated single crystalline Co disks on perpendicularly magnetized Ni/Cu(001) film to create artificial skyrmions whose topology can be tailored by changing the relative orientation between the vortex core polarity and the surrounding perpendicular magnetization.  In this way, we studied the topological effect of the skyrmion using Photoemission Electron Microscopy (PEEM).  By applying an in-plane magnetic field of various strengths, we find strong evidence that the annihilation of the vortex core depends on the topological skyrmion number of the system.

[1] 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, “Tailoring the topology of an artificial magnetic skyrmion”, Nature Communications 5, 4704 (2014).

[2] Kyoung-Woong Moon, Duck-Ho Kim, Soong-Geun Je, Byong Sun Chun, Wondong Kim, Z.Q. Qiu, Sug-Bong Choe, and Chanyong Hwang, “Skyrmion motions driven by oscillating under magnetic field oscillations”, Science Reports 5, 11055 (2015).

Biography

　　Ziqiang Qiu is a professor in the Physics Department of UC Berkeley. He received his Ph.D. in 1991 from the Johns Hopkins University. He has won awards of Outstanding Oversea Chinese Scholar, Chinese Academy of Science (2001) and Yangtze River Scholar, Minister of Education Department, P. R. China (2009). He has been elected the fellow of American Physical Society since 2010. He has published over 170 important papers, some of which have been published in Nature, Nature physics, Nature Communications and Phy. Rev. Lett.. He has given 140 invited reports in the international conference.

　　Professor Qiu’s major research interests is physics, novel behavior of the quantum magnetism in magnetic nanostructures, oscillatory interlayer coupling, the giant magnetoresistance, condensed matter experiment, technology applications, molecular beam epitaxy, artificial structures. Professor Qiu develops a fundamental understanding of the novel behavior of the quantum magnetism in magnetic nanostructures. As a magnetic structure is reduced to the nanometer size, quantum confinement of the electrons will generate fascinating properties such as the oscillatory interlayer coupling and the giant magnetoresistance. Investigation on these new phenomena will generate a great interest in the fundamental science and a great potential in the technology applications.