Imaging Atomic-Scale Distortions at Buried Oxide Interfaces.

Data de Início: 
quinta-feira, 27 Junho, 2019 - 16:00
Prof. Divine P. Kumah, North Carolina State University, Raleigh, N.C., U.S.A
Auditório Abrahão de Moraes - IFUSP



When crystalline materials are reduced to thicknesses on the order of a few atomic layers, their electronic and magnetic properties are significantly affected by tiny changes to their atomic arrangements and the presence of interfaces and surfaces. As devices become smaller and more efficient and the thickness of their material components approach the atomic scale, understanding and controlling these crystal distortions becomes crucial to controlling device performance. Therefore, it is challenging to predict these structural changes and thus, experimental techniques are required which can image atomic arrangements with sub-picometer scale resolution in a non-destructive way.

This talk will focus on the interfaces between atomic layers of transition metal complex oxide materials where structural, electronic and magnetic interactions at have led to the realization of a wide range of emergent properties. These properties include interfacial magnetism, superconductivity and high-mobility two dimensional electron gases and are directly linked to interfacial atomic-scale structural and chemical reconstructions. To understand and manipulate these emergent properties, we apply synchrotron-based surface diffraction and direct x-ray phase retrieval techniques to determine the atomic structures of crystalline complex oxide interfaces with picometer scale resolution. Our results have important implications for advancing our understanding of nanoscale phenomena and for the development of novel quantum materials for the next generation of devices.


  1. S. Koohfar, A.B. Georgescu, A. Penn, J.M. LeBeau, E. Arenholz, D.P. Kumah, Confinement of magnetism in atomically-thin La0.7Sr0.3CrO3/La0.7Sr0. 3MnO3 heterostructures. NPJ Quantum Materials 4, 25 (May 2019) arXiv:1710.07592
  2. S. Koohfar, A.S. Disa, M. Marshall, F.J. Walker, C.H. Ahn, C., D.P. Kumah, Structural Distortions At Polar Manganite Interfaces, Phys. Rev. B, 96, 024108, (2017).

This work is funded by the U.S. National Science Foundation CAREER Grant DMR-1751455.


Sobre o Palestrante: Prof. Dr. Divine Kumah is a Visitor Professor, hosted by Prof. Julio Larrea at Department of Physics Materials. His visit is part of the collaboration project “Novel Quantum Phenomena towards a New Generation of Thermoelectric Materials for Energy Harvesting” supported by the Universal Global Partnership Network (UGPN).


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