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Full-Text Articles in Electronic Devices and Semiconductor Manufacturing

Electromagnon Excitation In Cupric Oxide Measured By Fabry-Pérot Enhanced Terahertz Mueller Matrix Ellipsometry, Sean Knight, Dharmalingam Prabhakaran, Christian Binek, Mathias Schubert Feb 2019

Electromagnon Excitation In Cupric Oxide Measured By Fabry-Pérot Enhanced Terahertz Mueller Matrix Ellipsometry, Sean Knight, Dharmalingam Prabhakaran, Christian Binek, Mathias Schubert

Christian Binek Publications

Here we present the use of Fabry-Pérot enhanced terahertz (THz) Mueller matrix ellipsometry to measure an electromagnon excitation in monoclinic cupric oxide (CuO). As a magnetically induced ferroelectric multiferroic, CuO exhibits coupling between electric and magnetic order. This gives rise to special quasiparticle excitations at THz frequencies called electromagnons. In order to measure the electromagnons in CuO, we exploit single-crystal CuO as a THz Fabry-Pérot cavity to resonantly enhance the excitation’s signature. This enhancement technique enables the complex index of refraction to be extracted. We observe a peak in the absorption coefficient near 0.705 THz and 215 K, which corresponds …


Limitations Of Zt As A Figure Of Merit For Nanostructured Thermoelectric Materials, Xufeng Wang, Mark Lundstrom Jan 2019

Limitations Of Zt As A Figure Of Merit For Nanostructured Thermoelectric Materials, Xufeng Wang, Mark Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

Thermoelectric properties of nanocomposites are numerically studied as a function of average grain size or nanoparticle density by simulating the measurements as they would be done experimentally. In accordance with previous theoretical and experimental results, we find that the Seebeck coefficient, power factor and figure of merit, zT, can be increased by nanostructuring when energy barriers exist around the grain boundaries or embedded nanoparticles. When we simulate the performance of a thermoelectric cooler with the same material, however, we find that the maximum temperature difference is much less than expected from the given zT. This occurs because the …