Spectroscopy of materials under extreme conditions: evaluating magnetic frustration and spin liquid behavior in rare earth-containing Kagomé systems

Mar 13, 2012, 4:30 pm6:00 pm
Other See Notes


Event Description
In this presentation, I will overview the use of magneto-optical spectroscopy to investigate magnetic frustration and illustrate its use by assessing the spin liquid candidacy of a rare earth Langasite. This work was motivated by the large frustration index reported for Nd3Ga5SiO14, the principle contender for spin liquid behavior in this class of compounds, and questions about how low-lying crystal field levels of Nd3+ might influence the magnetic properties. To address these questions, we advantageously combined local probe photophysics and high magnetic field techniques to elucidate the low-lying electronic structure, bulk magnetic properties, and exchange interaction, the latter of which, if strong, would constitute an important signature of the elusive spin liquid state. Instead, we find that the bulk magnetic properties can be quantitatively explained assuming isolated Nd3+ sites and that the exchange interaction, critical for testing spin liquid character, is small (<0.01 meV). The small exchange interaction leads to a revised frustration factor of ~1 and rules out in Nd3Ga5SiO14 as a spin liquid, at least down to 100 mK. Held in the Edward C. Taylor Auditorium in the Frick Chemistry Building
Held in the Edward C. Taylor Auditorium in the Frick Chemistry Building