Colloquium: Dr. Chris WiebeDepartment of Chemistry University of Winnipeg Winnipeg, Manitoba
Dirac Strings and Magnetic Monopoles in Spin Ices
In the world of condensed matter physics, there has been a flurry of activity centered on the existence of “magnetic monopoles” in a strange group of materials known as “spin ices.” While the idea of a magnetic monopole has been around for quite some time (using magnetic “charge” as a computational tool since the time of Faraday), the theoretical grounding for magnetic monopoles was not made clear until the work of Paul Dirac. In this talk, I will outline the historical development of the idea of a “magnetic monopole," and then discuss how monopoles (and Dirac strings) manifest themselves in spin ices. Recent work on new spin ices, in which there is a high density of monopoles, will be mentioned, and the application of an idea in physical chemistry (the Debye-Hückel equation) will be shown to be an excellent approximation to describing monopoles as a magnetic “electrolyte” solution.