Dr. Shireen Adenwalla, Associate Professor
Physics & Astronomy
University of Nebraska - Lincoln
310E T. Jorgensen Hall
Lincoln, Nebraska 68588-0299
office: (402) 472-2709
Dr. Adenwalla's work involves structural characterization of materials, magnetic systems, polymers and the development of solid state neutron detectors.
In collaborations with Professor Ducharme's group, the structural changes of ferroelectric polymers across the ferroelectric transition are being investigated. The crystallinity of these Langmuir-Blodgett deposited polymers allows a study of their crystal structure and other properties usually attributed only to crystalline materials for e.g. the Debye Temperature, a concerted effort is being made to make a definitive measurement of the crystal structure and all possible phonon modes. We are also looking at interlayer coupling between ferroelectric layers of differing transition temperatures. Recent measurements at the Advanced Photon Source in order to look for coupling show initial evidence that such a coupling does indeed exist.
We have been investigating the effect of magnetic anisotropy on the coupling between ferromagnet and an antiferromagnet. Recently, we have investigated the interlayer coupling in out-of-plane magnetized layers separated by an insulating antiferromagnetic spacer and found evidence of oscillatory coupling. We plan to further investigate this phenomena using a variety of techniques, including x-ray magnetic scattering, transport, MOKE, and neutrons. We are also investigating the properties of sub-micron size features of both single layer and multilayer arrays and the effects of size, spacing and shape on the coupling and magnetic properties of these arrays.
In collaboration with Brian Robertson and Peter Dowben, B5C diodes are being developed for use as solid state neutron detectors. Working diodes have been fabricated and are being tested at a TRIGA medical reactor at the VA Medical Center in Omaha. If successful, these could have major implications for neutron detection, in terms of sensitivity, reliability, size and sturdiness.
This work is funded by the NSF, ONR and NRI.
The sweep rate dependence of the electrical control of magnetic coercivity, A. Mardana, Stephen Ducharme, S. Adenwalla, Journal of Applied Physics , 111 (2012) 56th Conference on Magnetism and Magnetic Materials (2011)
Domain size and structure in exchange coupled [Co/Pt]/NiO/[Co/Pt] multilayers A. Baruth and S. Adenwalla J.Phys. : Condens. Matter, 23, 376002 (2011)
Ferroelectric Control of Magnetic Anisotropy A. Mardana, Stephen Ducharme, and S. Adenwalla Nanoletters, 11, 3862 (2011)
Magnetization dynamics triggered by surface acoustic waves S. Davis, A. Baruth, and S. Adenwalla. Appl. Phys. Lett., 97, 232507 (2010)
Magnetoelectric effects in ferromagnetic cobalt/ferroelectric copolymer multilayer films A. Mardana, Mengjun Bai, A. Baruth, Stephen Ducharme and S. Adenwalla App. Phys. Lett., 97, 112904 (2010)
Boron Carbide based solid state neutron detectors: the effects of bias and time constant on neutron detection Nina Hong, John Mullins, Keith Foreman and S. Adenwalla J. Phys. D.: Appl. Phys., 43, 275101 (2010)
Temperature and set field dependence of exchange bias training effects in Co/NiO/[Co/Pt] heterostructures with orthogonal easy axes A. Baruth and S.Journal of Magnetism and Magnetic Materials, 322, 2051 (2010) Adenwalla
Ni doping of semiconducting boron carbide Nina Hong, M. A. Langell, Jing Liu, Orhan Kizilkaya, and S. Adenwalla J. Appl. Phys., 107, 024513 (2010)
“Effect of bias on neutron detection in thin semiconducting boron carbide films,” E. Day , M. J. Diaz, and S. Adenwalla, Journal of Physics D: Appl. Phys. 39, 2920 (2006).
“Modeling Solid-State Boron Carbide Low Energy Neutron Detectors,” C. Lundstedt, A. Harken, E. Day, B. W. Robertson, and S. Adenwalla, Nuclear Instruments and Methods in Physics Research A 562, 380-388 (2006).
“The Effect of Interlayer Interactions on the Ferroelectric-Paraelectric Phase Transition in Multilayered Thin Films of Vinylidene Fluoride-Trifluoroethylene Copolymers,” Jihee Kim, Hoydoo You, Stephen Ducharme, and S. Adenwalla, Journal of Physics Condensed Matter 19, 08206 (2007).
“Origin of the interlayer exchange coupling in [Co/Pt]/NiO/[Co/Pt] multilayers studied with XAS, XMCD, and micromagnetic modeling,” A. Baruth, D. J. Keavney, J. D. Burton, K. Janicka, E. Y. Tsymbal, L. Yuan, S. H. Liou, and S. Adenwalla, Physical Review B 74, 054419 (2006).
“Domain overlap in antiferromagnetically coupled [Co/Pt]/NiO/[Co/Pt] multilayers,” A. Baruth, L. Yuan, J. D. Burton, K. Janicka, E. Y. Tsymbal, S. H. Liou, and S. Adenwalla, App. Phys. Lett. 89, 202505 (2006).