Technical Summary: Measurement of free charge carrier properties in complex nanostructure materials and heterostructures is becoming increasingly indispensible for understanding of fundamental and new physical phenomena in such materials. Traditional electrical Hall effect instruments are limited in their ability to probe the free charge carrier properties, particularly in operation modes which are contactless, non-invasive, non-destructive and yet capable of spatially resolving the charge carrier behavior. This project aims to develop a low-operation-cost, feasible, easy-to-use, desk-top-style, and world-unique Optical Hall effect instrumentation for the 0.1 to 50 Terahertz (THz) spectral region for studying samples within magnetic fields up to 8 T, and in the temperature range between 4 K and 300 K. The new development measures the transverse and longitudinal optical birefringence at long wavelengths due to displacements of charge location in an external magnetic field, as a function of wavelength, magnetic field direction, and strength. The Optical Hall effect instrument allows understanding of charge and spin transport properties, and will greatly advance our understanding of multiferroic tunnel structures, magnetoelectric heterostructures, ferromagnetic, and ferroelectric polymer structures, magnetic, and piezoelectric hybrid nanostructures and novel solar cell materials and devices, for example. The instrumentation will be developed at the University of Nebraska-Lincoln (UNL), and will be used in collaboration between different Universities, National Laboratories and Companies working with electrical properties of nanostructure materials and devices. The proposal will integrate the education of graduate and undergraduate students with basic research and new instrumentation development, and will leverage with NSF-MRSEC QSPIN, 2 NSF-CAREER, and NSF-DMR program activities and inter-departmental and inter-collegiate collaborations within the University of Nebraska-Lincoln. The MRI development will promote productive partnerships for instrument development between UNL, and the J. A. Woollam Co., Inc. of Lincoln, Nebraska, the world-leading manufacturer of spectroscopic ellipsometry instrumentation.
Layman Summary: The motion of electrons and their positively charged counterparts - holes - in nanostructure materials is governed by new phenomena due to the confinement imposed by the nanostructure geometry and composition. Knowledge of the charge properties within such nanostructures will enable design of new materials and devices with capabilities far beyond current technology. Monitoring electron and hole motions within strong magnetic fields using polarized Terahertz and Far infrared light at frequencies up to ten thousand times faster than current desktop computer clock speed reveals their location and properties, and fundamental and new physical phenomena can be explored in such materials. Traditional methods require electrical contacts, which are difficult or simply impossible to attach to the nanostructures. The new and world-unique Optical Hall effect instrumentation employs frequencies which penetrate the nanostructures and screen their electron and hole properties without electrical contacts. Many innovations are expected from studying new multifunctional nanostructures for solar and energy restoring applications, for example. The instrumentation will be developed at the University of Nebraska-Lincoln (UNL), and will be used in collaboration between different Universities, National Laboratories and Companies working with electrical properties of nanostructure materials and devices. The proposal will integrate the education of graduate and undergraduate students with basic research and new instrumentation development, and promote productive partnerships between UNL, and the J. A. Woollam Co., Inc. of Lincoln, Nebraska, the world-leading manufacturer of spectroscopic ellipsometry instrumentation.
