Engineering topics

Eom, Professor Chang-Beom

Publications and source records attributed to Eom, Professor Chang-Beom.

4 records

DOE OSTI2012

Switchable Induced Polarization in LaAlO3/SrTiO3 Heterostructures

Demonstration of a tunable conductivity of the LaAlO3/SrTiO3 interfaces drew significant attention to the development of oxide electronic structures where electronic confinement can be reduced to the nanometer range. While the mechanisms for the conductivity modulation are quite different and include metal insulator phase transition and surface charge writing, generally it is implied that this effect is a result of electrical modification of the LaAlO3 surface (either due to electrochemical dissociation of surface adsorbates or free charge deposition) leading to the change in the twodimensional electron gas (2DEG) density at the LaAlO3/SrTiO3 (LAO/STO) interface. In this paper, using piezoresponse force microscopy we demonstrate a switchable electromechanical response of the LAO overlayer, which we attribute to the motion of oxygen vacancies through the LAO layer thickness. These electrically induced reversible changes in bulk stoichiometry of the LAO layer are a signature of a possible additional mechanism for nanoscale oxide 2DEG control on LAO/STO interfaces.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2012

Probing surface and bulk electrochemical processes on the LaAlO3-SrTiO3 interface

Local electrochemical phenomena on the surfaces of LaAlO3-SrTiO3 heterostructure are explored using unipolar and bipolar dynamic electrochemical strain microscopy (D-ESM). The D-ESM suggests the presence of at least two distinct electrochemical processes, including fast reversible low-voltage process and slow high-voltage process. The latter process is associated with static surface deformations in the sub-nm regime. These behaviors are compared with Kelvin Probe Force Microscopy hysteresis data. The possible origins of observed phenomena are discussed and these studies suggest that charge-writing behavior in LAO-STO include strong surface/bulk electrochemical component and are more complicated than simple screening by surface adsorbates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2012

Multifunctional Oxide Heterostructures

This book is devoted to the rapidly developing field of oxide thin-films and heterostructures. Oxide materials combined with atomic-scale precision in a heterostructure exhibit an abundance of macroscopic physical properties involving the strong coupling between the electronic, spin, and structural degrees of freedom, and the interplay between magnetism, ferroelectricity, and conductivity. Recent advances in thin-film deposition and characterization techniques made possible the experimental realization of such oxide heterostructures, promising novel functionalities and device concepts.

Tsymbal, E Y↗

DOE OSTI2012

Structure, physical properties, and applications of SrRuO3 thin films

SrRuO{sub 3} is endowed with three remarkable features. First, it is a moderately correlated material that exhibits several novel physical properties; second, it permits the epitaxial growth of essentially single-crystal films; and third, because it is a good conductor, it has attracted interest as a conducting layer in epitaxial heterostructures with a variety of functional oxides. In this review, the present state of knowledge of SrRuO{sub 3} thin films is summarized. Their role as a model system for studying magnetism and electron transport characterized by intermediate electron correlation and large magnetocrystalline anisotropy is demonstrated. The materials science of SrRuO{sub 3} thin film growth is reviewed, and its relationship to electronic, magnetic, and other physical properties is discussed. Finally, it is argued that, despite all that has been learned, a comprehensive understanding of SrRuO{sub 3} is still lacking and challenges remain.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗