Terahertz spectroscopy of strongly frustrated helical magnet Fe<sub>3</sub>PO<sub>4</sub>O<sub>3</sub>
ORAL
Abstract
The hexagonal lattice in Fe3PO4O3 is made up of three triangularly coordinated Fe units that make the magnetic interactions strongly geometrically frustrated. Along the c-axis, layers of these triangular units arrange in a larger, triangular lattice pattern, making the magnetic interactions also frustrated. Even with this level of frustration, magnetic order occurs below TN ~ 165 K in the form of a long-wavelength helical pattern. We use time-domain terahertz (THz) spectroscopy to study the magnetic excitations in powder samples of this material. We find an overall softening of the magnetic spectrum around TN, but with no well-defined sharp resonant modes. However, below ~40 K we find a well defined resonant mode centered around ~ 900 GHz suggesting the existence of an additional transition below this temperature. We will discuss the possible explanations of this behavior within linear spin-wave theory.
*Patial support was provided by the Center for Emergent Materials, an NSF MRSEC, under grant DMR-1420451.
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Presenters
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Nicholas Crescimanno
- Center for Emergent Materials. Department of Physics, The Ohio State University