EUO-Based Multifunctional Heterostructures
Final rept. Apr 2010-Jun 2015
CORNELL UNIV ITHACA NY OFFICE OF SPONSORED PROGRAMS
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Using molecular-beam epitaxy heterostructures were grown in which EuO was controllably doped, strained, patterned, and integrated with other materials to enable novel effects and emerging device concepts to be explored. These included 1 achieving a drastic increase of the magnetoresistance and the metal-insulator transition resistance ratios of doped EuO by interfacing this semiconductor with niobium the observed effect is general and may be applied to any metalsemiconductor interface where the semiconductor shows large Zeeman splitting under magnetic field, 2 understanding the changes in electronic structure and Fermi-surface reconstruction that occur as doped EuO progresses through the ferromagnetic metal-insulator transition a lack of carrier activation arises from defect states near the Gamma point, 3 demonstrating that ultrafast optical pulses can be used to strengthen or weaken the magnetic order of doped EuO by 10 in 3 ps, 4 establishing a new method for making EuO films by high-vacuum techniques with perfection and properties previously accessible only by ultra-high vacuum methods, and 5 straining EuO by over 6 to achieve the simplest and highest temperature strong multiferroic known simultaneously ferromagnetic and ferroelectric.