Daniel Currie
Texas State University
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Publication
Featured researches published by Daniel Currie.
Journal of Applied Physics | 2013
Ryan Laughlin; Daniel Currie; Rocio Contreras-Guererro; Aruna Dedigama; Weerasinghe Priyantha; Ravindranath Droopad; Nikoleta Theodoropoulou; Peng Gao; Xiaoqing Pan
The integration of oxides with semiconductors is important for the technological advancement of the next generation electronics. Concomitant ferroelectric and antiferromagnetic (AF) behavior is demonstrated in single crystal BiFeO3 (BFO) films grown on 20 nm SrTiO3 (STO) virtual substrates on Si(100) using molecular beam epitaxy (MBE). STO thin films are grown in an oxide MBE chamber by co-deposition of Sr, Ti, and molecular O2. Careful control of the O2 during nucleation produced commensurate growth of STO on Si. The sequence of the steps allows for the suppression of an amorphous SiO2 layer. This STO(20 nm)/Si structure was used as a virtual substrate for MBE deposition of BFO on Si without breaking vacuum. BFO was deposited using Fe and O2 plasma with an overpressure of Bi flux, the growth rate was controlled by the incoming Fe flux. The reflection high energy electron diffraction image shows a 2-D growth front with a 6-fold surface reconstruction under optimized O2 pressure of 5 × 10−8 mbar. Cross-sectional transmission electron microscopy (TEM) confirms the high crystallinity of the films and shows sharp, atomically flat interfaces. The selected area diffraction pattern (SADP) reveals that BFO grows in a distorted rhombohedral crystal structure. X-ray diffraction does not show formation of second phases and is consistent with the TEM and SADP results. The BFO films show AF behavior with a Neel temperature that exceeds 350 K, as expected (TN = 673 K) and with a residual ferromagnetic behavior that decreases with film thickness and is consistent with the G-type AF due to the canted spins. The saturation magnetization per unit volume for a 40 nm thick film was 180 emu/cm3 at an in-plane magnetic field of 8 kOe. The ferroelectric behavior of the films was verified using piezoresponse force microscopy.The integration of oxides with semiconductors is important for the technological advancement of the next generation electronics. Concomitant ferroelectric and antiferromagnetic (AF) behavior is demonstrated in single crystal BiFeO3 (BFO) films grown on 20 nm SrTiO3 (STO) virtual substrates on Si(100) using molecular beam epitaxy (MBE). STO thin films are grown in an oxide MBE chamber by co-deposition of Sr, Ti, and molecular O2. Careful control of the O2 during nucleation produced commensurate growth of STO on Si. The sequence of the steps allows for the suppression of an amorphous SiO2 layer. This STO(20 nm)/Si structure was used as a virtual substrate for MBE deposition of BFO on Si without breaking vacuum. BFO was deposited using Fe and O2 plasma with an overpressure of Bi flux, the growth rate was controlled by the incoming Fe flux. The reflection high energy electron diffraction image shows a 2-D growth front with a 6-fold surface reconstruction under optimized O2 pressure of 5 × 10−8 mbar. Cross-sec...
Applied Physics Letters | 2015
Ryan J. Cottier; Nathan Steinle; Daniel Currie; Nikoleta Theodoropoulou
We investigate the effect of strain and oxygen vacancies (VO) on the crystal and optical properties of oxygen deficient, ultra-thin (4–30 nm) films of SrTiO3-δ (STO) grown heteroepitaxially on p-Si(001) substrates by molecular beam epitaxy. We demonstrate that STO band gap tuning can be achieved through strain engineering and show that the energy shift of the direct energy gap transition of SrTiO3-δ/Si films has a quantifiable dimensional and doping dependence that correlates well with the changes in crystal structure.
Journal of Polymer Science Part B | 2012
David J. Irvin; John D. Stenger-Smith; Gregory R. Yandek; Jamie R. Carberry; Daniel Currie; Nikoleta Theodoropoulou; Jennifer A. Irvin
Bulletin of the American Physical Society | 2017
John Miracle; Dean Koehne; Ryan Cottier; Daniel Currie; Nikoleta Theodoropoulou
Bulletin of the American Physical Society | 2017
Dean Koehne; Ryan Cottier; Daniel Currie; John Miracle; C. H. Swartz; Nikoleta Theodoropoulou
Bulletin of the American Physical Society | 2016
Parisa Jalili Shafighi; Ryan Cottier; Daniel Currie; Barry Koehne; Andrew Johnson; Joshua P. Veazey; Nikoleta Theodoropoulou
Bulletin of the American Physical Society | 2015
Ryan Cottier; Daniel Currie; Nikoleta Theodoropoulou
Bulletin of the American Physical Society | 2015
Nikoleta Theodoropoulou; Daniel Currie; Ryan Cottier; Arturo Ponce-Pedraza; Jesus Cantu; Oscar Villarreal
Bulletin of the American Physical Society | 2015
Nathan Steinle; Barry Koehne; Ryan Cottier; Daniel Currie; Nikoleta Theodoropoulou
Bulletin of the American Physical Society | 2014
Ryan Cottier; Daniel Currie; Nikoleta Theodoropoulou