Highly Frustrated Magnetism 2008

Student Tutorials

Thanks to the generous support by the European Science Foundation we are able to organize a Student Tutorial on Sunday September 7, 2008.

The lectures are now available!

Tutorial Lecturers will be

14:00 John E. Greedan (Mcmaster, Hamilton) Lecture Greedan
14:50 Jason Gardner (NIST, Gaithersburg) Lecture Gardner
15:40 Colin Broholm (Baltimore) Lecture Broholm

Abstracts

Download the PDF!

Highly Frustrated Magnets - Materials and Materials Preparation

by J.E. Greedan

Department of Chemistry and the Brockhouse Institute for Materials Research, McMaster University, Hamilton, Canada

The basic ideas of geometric frustration, which involves the subversion of the Third Law of Thermodynamics, will be introduced, including the canonical frustrated lattices, the frustration index and the role of spin fluctuations. Families of real geometrically frustrated materials will be reviewed in terms of crystallography and crystal chemistry. These will include, but will not be restricted to, the pyrochlores, jarosites, spinels, herbertsmithites, anhydrous alums, ordered rocksalt, garnet and ordered perovskite materials. As many of these are transition metal oxides, the principles of the preparation of such compounds, including the growth of single crystals will be described. The importance of materials characterization will be stressed.

Some common and not so common bulk properties seen in geometrically frustrated magnets

by J. S. Gardner

Indiana University, 2401 Milo B. Sampson Lane, Bloomington, Indiana 47408 and NIST Center for Neutron Research, NIST, Gaithersburg, MD 20899-6102, USA

I will give an overview of some common features seen in the bulk of geometrically frustrated magnets (GFM). This will include susceptibility, magnetisation, specific heat, muon spin relaxation and nuclear magnetic resonance. By going through a couple of GFM examples, I hope to demonstrate the basic signatures often seen. These features include the high frustration index, zero point entropy, plateaus in magnetisation etc.. Of course this field would not be so interesting if everything was "common" so I will also highlight some of the unique characteristics seen in GFM.

Probing Frustration through Neutron Scattering

by Colin Broholm

Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA & NIST Center for Neutron Research, Gaithersburg, MD, USA

Frustrated magnets are characterized by strong fluctuations and anomalous non-collinear and short ranged order. While a wide range of experimental tools are necessary for a full understanding of these complex materials, neutron scattering can provide exquisite details regarding atomic scale structure and dynamics. In this tutorial I review the theoretical formalism behind neutron scattering and describe the corresponding instrumentation, techniques, and analysis. Examples of key neutron scattering experiments on frustrated magnets will illustrate the power of the technique and its limitations. I then describe the exciting prospects for new information about frustrated magnetism from new sources and instrumentation. The tutorial is geared towards experimentally and theoretically oriented graduate students and post docs with an interest in frustrated magnetism but little or no prior knowledge of neutron scattering.