Roman Engel-Herbert

Roman Engel-Herbert
  • Assistant Professor of Materials Science and Engineering
N-232 Millennium Science Complex
(814) 867-4325

Bio

Roman Engel-Herbert received a Diploma in Physics from the Friedrich-Schiller University Jena, Germany. He later joined the Paul-Drude-Institute for Solid State Electronics for his graduate studies under the direction of Klaus H. Ploog and Thorsten Hesjedal and received a Ph.D. degree in Experimental Physics from the Humboldt University Berlin. He then followed an invitation to the University of Waterloo in Canada before he accepted a postdoc position in the Materials Department at the University of California Santa Barbara. Dr. Engel-Herbert joined the faculty of Materials Science and Engineering at Penn State University in 2010. His current research interests are the growth of binary and complex oxides using thin film deposition techniques and their integration with conventional semiconductors as well as the analysis of magnetic domain structures.

In 2014 Dr. Engel-Herbert was selected to receive the prestigious NSF Career Award.  His CAREER project is jointly funded by Electronic and Photonic Materials and Ceramic programs.  For more information about this project click here.

Academic Training

Ph.D. in Physics, Friedrich-Schiller University

Awards and Accomplishments

NSF CAREER Award (2014)

Research

Research efforts are focused on the growth and characterization of oxide thin films. This class of materials has an unparalleled spectrum of physical properties which makes them very interesting for a variety of applications ranging from energy generation, sensors and actuators to memory and logic device concepts.  The monolithic integration of oxide thin films to cross-couple different functionalities, novel interface phenomena, epitaxial stabilization of unfavorable phases and strain engineering provide additional degrees of freedom that are largely unexplored, which further extend the opportunities to tailor material properties. Although oxide films can be grown with high structural perfection, intrinsic material properties might be obscured by a high level of unintentional defects.

Molecular beam epitaxy (MBE) is the main synthesis method employed by this group. The system design facilitates the deposition of metal organic molecules and thus combines low energetic deposition techniques in a unique way, dubbed "Hybrid MBE". Stoichiometric control and suppression of defect formation during growth as well as doping strategies are addressed. Structural characterization methods encompass X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). Hall measurements and admittance spectroscopy are used for electrical characterization.

Another research area are magnetic domain structures in confined geometries with nanoscale dimensions. Domain arrangements, their formation and stability in the presence of an external magnetic field are studied by magnetic force microscopy. Current induced magnetization dynamics, such as spin transfer torque magnetization reversal and domain wall motion, are investigated using micromagnetic simulation. Magnetic nanostructures are building blocks of spin-electronic devices and the study of these phenomena is imperative for their successful application in the area of information technology.

Research Interests: 

  • Growth of oxide thin films by molecular beam epitaxy

  • Interface related phenomena of heteroepitaxial oxide thin films

  • Integration of oxides with conventional semiconductors

  • Imaging and simulation of magnetic domain structures

Technology Impacted By Research: 

  • Power generation and energy harvesting technology (thermoelectrics, photovoltaics)

  • Information technologies (nonvolatile memories, logic devices)

 

Publications
Noted Publications:
  1. "Epitaxial SrTiO3 films with electron mobilities exceeding 30,000 cm2V-1s-1," J. Son, P. Moetakef, B. Jalan, O. Bierwagen, N.J. Wright, R. Engel-Herbert, S. Stemmer, Nature Materials, 9 482 (2010).
  2. "Growth of high-quality SrTiO3 films using a hybrid molecular beam epitaxy approach," B. Jalan, R. Engel-Herbert, N.J. Wright, S. Stemmer, Journal of Vacuum Science and Technology A, 27 (2) 461-464 (2009).
  3. "Metal-oxide-semiconductor capacitors with ZrO2 dielectrics grown on In0.53Ga0.47As by chemical beam deposition" R. Engel-Herbert, Y. Hwang, J. Cagnon, S. Stemmer, Applied Physics Letters, 95 (6) 062908 (2010).
  4. "Three-dimensional micromagnetic domain structure of MnAs films on GaAs(001): Experimental imaging and simulation," R. Engel-Herbert, T. Hesjedal , D. M. Schaadt, Physical Review B, 75 094430 (2007).
  5. "Field-dependence of micromagnetic domain patterns in MnAs films," R. Engel-Herbert, T. Hesjedal, J. Mohanty, D.M. Schaadt, K.H. Ploog, Journal of Applied Physics, 98 (6), 063909 (2005).