Unusual Thermal Properties in Magnetic MnFe<sub>2</sub>O<sub>4</sub> and FeMn<sub>2</sub>O<sub>4</sub> Single Crystals
ORAL
Abstract
Materials that form the AB2O4-type spinel structure are known to exhibit geometric frustration, as the A sublattice forms diamond-like structure and B sublattice is pyrochlore-like. They are thus promising candidates for studying unconventional thermal and magnetic properties. Here, we report thermal conductivity, thermopower, and specific heat in magnetic spinel MnFe2O4 and FeMn2O4 single crystals. One remarkable feature is their low thermal conductivity in a wide temperature range (2 K and 400 K) with a maximum value of ~ 2.0 W/K-m, which is usual for single crystalline materials. Furthermore, both the low-temperature thermal conductivity and specific heat exhibit T3/2 dependence instead of T3 behavior. This strongly suggests that heat in these magnetic spinel materials is predominantly carried by magnons, while phonons exhibit glass-like behavior, conducting little heat. The latter should be attributed to geometric frustration inherent in spinel materials.
*This work was supported by DoE through DE-SC0016315.
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Presenters
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Roshan Nepal
- Physics and Astronomy, Louisiana State Univ - Baton Rouge
- Physics and Astronomy, Louisiana State University