Experimental Condensed Matter Physics
Distinguished R&D Staff, Neutron Scattering Division
Oak Ridge National Laboratory
Phone: (505) 901-0534
Thin films and nanostructures provide convenient platforms to exploit novel functional behavior for technological applications. Applications include: permanent magnets, quantum information technologies, spintronics, low power electronics, memristors etc., as well as energy conversion, e.g., spin Seebeck currents and conventional thermoelectrics. Thin films and interfaces also enable topologically protected (against annihilation) magnetic order, such as topological insulators and skyrmions. My research is focused on understanding novel materials properties that stem from interfaces—regions between dissimilar materials whose structure enables ground states of matter not observed in the constituent components. Examples include combinations of ferroelectric, ferromagnetic, ferroelastic and ferrotoroidic order parameters. My experiments involve developing and using instrumentation techniques that allow control of various conjugate fields during neutron scattering experiments. A second research effort involves characterization of turbulent flow around objects under conditions of large Reynolds number using neutron beams and cryogenic He.
I seek highly motivated graduate students and postdocs who are interested in participating in experimental research to understand and control interfacial properties that lead to new functional materials. Ability to work in a collaborative laboratory and user facility environments is essential. If you are interested please e-mail or call me.
Please see my Google Scholar profile for a complete list of publications.
141. Er-Jia Guo, Ryan D. Desautels, David Keavney, Andreas Herklotz, T. Zac Ward, Michael R. Fitzsimmons and Ho Nynung Lee, Lee, Switchable orbital polarization and magnetization in strained LaCoO3 films, Phys. Rev. Mater 3, 014407 (2019). http://dx.doi.org/10.1103/PhysRevMaterials.3.014407
140. Er-Jia Guo, Manuel A. Roldan, Xiahan Sang, Satoshi Okamoto, Timothy Charlton, Haile Ambaye, Ho Nyung Lee, and Michael Fitzsimmons, Influence of chemical composition and crystallographic orientation on the interfacial magnetism in BiFeO3/La1-xSrxMnO3 superlattices, Phys. Rev. Mater., 2, 114404 (2018). http://dx.doi.org/10.1103/PhysRevMaterials.2.114404
139. J. Walter, T. Charlton, H. Ambaye, M.R. Fitzsimmons, P.P. Orth, R.M. Fernandes and C. Leighton, Giant Electrostatic Modification of Magnetism via Electrolyte-Gate-Induced Cluster Percolation in La1-xSrxCoO3-d, Phys. Rev. Mater., 2, 111406 (2018). http://dx.doi.org/10.1103/PhysRevMaterials.2.111406
*138. Er-Jia Guo, Manuel Roldan, Timothy Charlton, Zhaoliang Liao, Qiang Zheng, Haile Ambaye, Andreas Herklotz, Zheng Gai, T. Zac Ward, Ho Nyung Lee, and Michael R. Fitzsimmons, Removal of Magnetic Dead Layer by Geometric Design, Adv. Funct. Mater., 28, 1800922 (2018). http://dx.doi.org/10.1002/adfm.201800922
*137. E. Guo, Y. Liu, C. Sohn, R.D. Desautels, A. Herklotz, Z. Liao, J. Nichols, J.W. Freeland, M.R. Fitzsimmons, H.N. Lee, Oxygen Diode Formed in Nickelate Heterostructures by Chemical Potential Mismatch, Advanced Materials 30, 1705904 (2018). http://dx.doi.org/10.1002/adma.201705904
136. Q. Wang A.P. Chen, E.J. Guo, M.A. Roldan, Q.X. Jia and M.R. Fitzsimmons, An upper limit on the influence of elastic bending stress on the saturation magnetization of La0.8Sr0.2MnO3, Physical Review B 97, 014437(2018). https://dx.org/10.1103/PhysRevB.97.014437
135. T. Wang, C.Y. Jiang, T.O. Farmer, L. Debeer-Schmitt, J.F. Wenzel, L. McDonald, J.L. Robertson, M.R. Fitzsimmons and X. Tong, New polarized small angle neutron scattering capability at the High Flux Isotope Reactor, Physica B 551, 492 (2017). https://doi.org/10.1016/j.physb.2017.12.041
134. A. Huon, D. Lee, A. Herklotz, M.R. Fitzsimmons, H.N. Lee and S.J. May, Effect of chemical pressure on the electronic phase transition in Ca1-xSrxMn7O12 films, Applied Physics Letters Materials 5, 096105 (2017). https://doi.org/10.1063/1.4994089
*133. Er-Jia Guo, Timothy Charlton, Haile Ambaye, Ryan Desautels, Ho Nyung Lee and Michael Fitzsimmons, Orientation control of interfacial magnetism at La0.67Sr0.33MnO3/SrTiO3 interfaces, ACS Applied Materials and Interfaces, 9, 19307 (2017). http://pubs.acs.org/doi/abs/10.1021/acsami.7b03252
*132. Er-Jia Guo, Jonathan R. Petrie, Manuel A. Roldan, Qian Li, Ryan D. Desautels, Timothy Charlton, Andreas Herklotz, John Nichols, Johan van Lierop, John W. Freeland, Sergei V. Kalinin, Ho Nyung Lee, and Michael R. Fitzsimmons, Spatially resolved large magnetization in ultrathin BiFeO3, Advanced Materials, 1700790 (2017). http://dx.doi.org/10.1002/adma.201700790
*131. Aiping Chen, Qiang Wang, Michael R. Fitzsimmons, Erik Enriquez, Marcus Weigand, Zach Harrell, Brian McFarland, Xujie Lü, Paul Dowden, Judith L. MacManus-Driscoll, Dmitry Yarotski, and Quanxi Jia, Hidden Interface Driven Exchange Coupling in Oxide Heterostructures, Advanced Materials 1700672 (2017). http://dx.doi.org/10.1002/adma.201700672
*130. A. Herklotz, E. Guo, A.T. Wong, T.L. Meyer, S. Dai, T.Z. Ward, H.N. Lee, M. R. Fitzsimmons, Reversible control of interfacial magnetism through ionic liquid assisted polarization switching, NanoLetters, 17, 1665 (2017). http://dx.doi.org/10.1021/acs.nanolett.6b04949
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