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学术报告    Skyrmion Lattices in Antiferromagnetic Systems


【报告题目】 Skyrmion Lattices in Antiferromagnetic Systems
【报 告 人】 Daniel Cabra
              Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata, Argentina
【时 间】 2017-06-09     星期五 10:00
【地 点】 北校区物理楼106

【报告摘要】

We present the results of a study of the classical antiferromagnetic Heisenberg model on the triangular lattice with Dzyaloshinskii-Moriya interactions in a magnetic field. We focus in particular on the emergence of a composite spin crystal phase, dubbed antiferromagnetic skyrmion lattice, that was recently observed in [Phys. Rev. B 92, 214439 (2015)] for intermediate fields. This complex phase can be made up from three inter-penetrated skyrmion lattices, one for each sub-lattice of the original triangular one. We present our numerical results in detail and the explicit construction of the low-energy effective action that reproduces the correct phenomenology. This effective action could serve as a starting point to study the coupling to charge carriers, lattice vibrations, structural disorder and transport phenomena.


【报告人简介】

Prof. Daniel Cabra has started his career at the University of La Plata, Argentine and did his PhD working in CFT motivated by String Theory at the time. Then he moved to Heidelberg Universität for a postdoc, where he started to get interested in more applied problems. At a later postdoc in the ICTP, Trieste he started working in the application of Field Theory to Condensed Matter problems which is what ha has been doing since then.

He has spent 7 years as a full professor in France and since 2009 and returned to his home country, where he has managed to settle a very active group of 15 people. The group has many international collaborations with groups in France, Italy, Switzerland, Spain, etc.

He is mainly interested in the study of strongly correlated systems using a combination of theoretical and numerical techniques. 

Prof. Cabra has done some important contributions in the study of spin chains and ladders in a magnetic field and also in Hall effect, in collaboration with E. Fradkin. Last year his group had a successful collaboration with experimentalists from La Plata and St. Andrews on spin ice systems, published in Nat. Comm., where they have shown that vibrations/disorder are a crucial ingredient to get the right physics.

One of the main subjects he is interested at present is the appearance of Skyrmion lattices in 2D spin systems, which is the main subject of his talk today.


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