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Research from TANMS 3D Team Featured on Advances in Engineering

posted Aug 30, 2018, 10:44 AM by Tsai-Tsai O-Lee   [ updated Aug 30, 2018, 10:44 AM ]
Research recently published by Dr. Roberto Lo Conte, postdoctoral researcher under Professor Jeffrey Bokor at the UC Berkeley Department of Electrical Engineering and Computer Science was featured online by Advances in Engineering (AIE).  The paper published in Nano Letters titled "Influence of Nonuniform Micron-Scale Strain Distributions on the Electrical Reorientation of Magnetic Microstructures in a Composite Multiferroic Heterostructure" was identified by AIE selection committee as a key scientific article contributing to excellence in science and engineering research.

The research by Dr. Lo Conte and the TANMS 3D Thrust demonstrated a systematic micron-scale study of the physical mechanisms which drive a PMN-PT/Ni multiferroic actuator.  Findings as such contribute to a promising path toward the development of ultralow power magnetoelectric devices.

Abstract
Composite multiferroic systems, consisting of a piezoelectric substrate coupled with a ferromagnetic thin film, are of great interest from a technological point of view because they offer a path toward the development of ultralow power magnetoelectric devices. The key aspect of those systems is the possibility to control magnetization via an electric field, relying on the magneto-elastic coupling at the interface between the piezoelectric and the ferromagnetic components. Accordingly, a direct measurement of both the electrically induced magnetic behavior and of the piezo-strain driving such behavior is crucial for better understanding and further developing these materials systems. In this work, we measure and characterize the micron-scale strain and magnetic response, as a function of an applied electric field, in a composite multiferroic system composed of 1 and 2 μm squares of Ni fabricated on a prepoled [Pb(Mg1/3Nb2/3)O3]0.69–[PbTiO3]0.31 (PMN–PT) single crystal substrate by X-ray microdiffraction and X-ray photoemission electron microscopy, respectively. These two complementary measurements of the same area on the sample indicate the presence of a nonuniform strain which strongly influences the reorientation of the magnetic state within identical Ni microstructures along the surface of the sample. Micromagnetic simulations confirm these experimental observations. This study emphasizes the critical importance of surface and interface engineering on the micron-scale in composite multiferroic structures and introduces a robust method to characterize future devices on these length scales.

About the Author
Dr. Roberto Lo Conte has been important member of the TANMS 3D Thrust.  His scientific interests focus on studying new magnetic materials systems useful for the development of energy efficient spintronic devices. He began is academic career in Italy, obtaining his bachelor degree and subsequently his master degree in Physics Engineering at the Politecnico di Milano, with a final project focused on the fabrication and characterization of a magneto-optic device for the development of a metallic spin-flip based laser. Such a project was carried out at the Royal Institute of Technology (KTH) in Stockholm, Sweden, where Dr. Lo Conte spent two years as a Double Degree student and obtained his Master of Science in Engineering degree. In 2012 he moved to Germany for his PhD in Applied Physics at the Johannes Gutenberg University of Mainz, where he graduated in 2015 with a thesis on “Magnetic nanostructures with structural inversion asymmetry”.

In 2016 he joined the University of California at Berkeley as a post-doctoral researcher in the Electrical Engineering and Computer Science department, where he investigated multiferroic heterostructures with the intent of developing new magnetoelectric technologies for energy efficient applications.

Today Dr Lo Conte is a Marie Curie Fellow at the University of Hamburg in Germany and a post-doctoral research associate at the University of California at Berkeley, in the Materials Science and Engineering department, studying magnetic multilayers hosting topologically non-trivial spin states.

SOURCES:
Advances in Engineering: https://advanceseng.com/strain-distributions-magnetoelectric-multiferroic-devices-revealed/
Nano Letters: https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.7b05342