英超联赛买球

英超联赛买球:CMP Seminars

Pyrochlore Magnets: An exceptional playground of model magnets

Jason S Gardner Songshan Lake Materials Laboratory, Dongguang
Mon, 2019-10-21 13:30 - 14:30
Room742 , New Science Building NO.5

It is now well appreciated that the combination of certain spin-spin interactions and lattice symmetries leads to phenomena known broadly as geometrical frustration.  The spin system under question cannot simultaneously satisfy all of its near neighbour pair-wise exchange interactions and the resulting ground state can have a large degeneracy, or under constrained.

A sublattice of corner sharing tetrahedra can be shown to be more frustrated than a triangular latter under similar constraints. Pyrochlore oxides with the general formula  A2B2O7, as well as spinels and the C15-type Laves phase materials can possess a magnetic sublattice of corner sharing tetrahedral making them ever-present in the solid state.

Using some of the earlier work on pyrochlore oxides, I will demonstrate the numerous states of matter seen in pyrochlore oxides.  I will then discuss in more detail the Spin Ice ground state and our recent attempts to find new variants on this phase of magnetism. These studies include making samples under high pressure and chemical substitutions. Knowing the spin-spin correlations, in time and space, are critical to understanding these quantum magnets and neutron scattering is a powerful probe to acquiring these data. 

Jason S Gardner is a condensed matter physicist with a specific interest in quantum beam experiments.   For 15 years he has worked for several international user facilities, and visited many more.  Dr Gardner is a Fellow of both the American Physical Society and the Institute of Physics (UK), was Editor-in-Chief of the Journal of Physics: Condensed Matter (2012-2019) and before coming to China a Group Leader at the Australian Center for Neutron Scattering. He has published over 170 journal articles and given more than 100 oral presentations.  He is a strong supporter for international collaborations and has brought many together at international conferences and scientific schools, national and international workshops that he has organized. 

 

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