ChEMS Seminar: Nanoscale Heat Transport in Complex Oxide Thin Films

Friday, May 8, 2015 - 3:00 p.m. to Saturday, May 9, 2015 - 3:55 p.m.
McDonnell Douglas Engineering Auditorium (MDEA)

Professor Jayakanth Ravichandran
Department of Chemical Engineering and Materials Science
University of Southern California

Thin film growth of high quality heterostructures and superlattices has led to observations of exotic phenomena not observed in bulk systems and the realization of several device applications. For several years, growth of heterostructures, with sharp interfaces and low defect density, has been the domain of conventional semiconductors. Recently, such advances have been extended to other materials such as oxides, particularly complex oxides1. Much of the applications of such advances (both oxides and semiconductors) have focused on electronic, dielectric or optical effects. Most thermal transport phenomena have been considered classical until the widespread employment of nano/microscale heat transport measurement techniques in the past two or so decades. I will first review the evolution of oxide thin film growth techniques and the advances in material properties specifically thermal properties in complex oxide thin films. In the talk, I will discuss two cases, where nanoscale thermal transport has enabled both the observation of new phenomena and benchmarking the materials quality. First, I will show an example, where thermal transport can act as a probe for material quality in oxide heterostructures (specifically line and point defects) 2. In the second part, I will show that perovskite superlattices are a model system to observe a crossover from incoherent to coherent phonon transport3, which has been elusive in other semiconductor superlattice systems. This observation opens up new possibilities to realize low thermal conductivity systems and components for phonon optics.

References:
[1] D. G. Schlom, L-Q. Chen, et. al., J. Am. Ceram. Soc. 91, 2429 (2008).
[2] D-W. Oh, J. Ravichandran et. al., Appl. Phys. Lett. 98, 221904 (2011).
[3] J. Ravichandran, A. K. Yadav et. al., Nat. Mater. 13, 168 (2014).

 

Bio:  Jayakanth Ravichandran is an Assistant Professor in the Mork Family Department of Chemical Engineering and Materials Science at University of Southern California. He received his undergraduate degree in Metallurgical Engineering from Indian Institute of Technology at Kharagpur. He received his PhD from University of California at Berkeley, followed by post-doctoral appointments at Columbia University and Harvard University. His research interests are in synthesis, characterization and physical properties of heterostructures of complex materials such as complex oxides, chalcogenides etc.