Multiferroic and quantum fluctuations in single chiral langasite materials

Chris Stock (School of Physics & Astronomy, University of Edinburgh)

Multiferroics are systems where both magnetic and ferroelectric order parameters are coupled. Materials that are structural chiral and host magnetic ions are natural candidates for displaying such properties. In this seminar, I will discuss the magnetism and interactions in the iron based langasite compound Ba3NbFe3Si2O14. This system is based upon chains of trimers forming a "Toblerone" type lattice. The system is unique as single crystals are magnetically and structural chiral with only one domain present. The magnetic interactions will be discussed to show that there is strong coupling between magnetic and crystalline chirality through symmetric exchange. I will then go on to discuss the trimer structure and how this feature changes the properties of langasite from behaving like a classical high-spin magnet to that of low-dimensional magnet with intrinsic j=1/2 degrees of freedom where strong quantum fluctuations are present.

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