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Dipartimento di Fisica - Politecnico di Milano

[01/10/2019 - 11:30]

Dr. Nicolas Pavlopoulos (Technion University, Haifa)

 

"Chasing a Plastic Garnet: Polymer-Nanoparticle Faraday Rotators with High Verdet"

 

mar 01/10/2019 - 11:30 - Aula Rossa, Dipartimento di Fisica

 

Abstract


When polarized light interacts with a magneto-optically (MO) active material in a magnetic field, rotation of the plane of polarization is observed – a phenomenon known as the Faraday Effect – the strength of which depends on a material’s intrinsic Verdet constant. Due to the generally weak nature of the MO-effect in the visible/near-IR range, the use of such materials in key applications (ie optical circuitry, magnetic sensing) are limited by large device footprints and high field strengths. Thus, access to new high Verdet materials is key to device miniaturization and enhanced sensitivity. To gain insights into the structure-property relationships governing material Verdet constants, we developed hybrid systems composed of MO-active nanoparticles of variable size and loading embedded in low activity polymer matrices. New synthetic protocols to access high Verdet nanocrystals with tunable surface chemistry were found to be key to obtaining hybrid systems with up to 15 wt% particle loading and high optical transparency. Using multilayer solution processing, devices with Verdet constants up to 20x greater than that of commercially available garnet crystals can now be prepared at a fraction of the cost. In addition to synthetic and measurement considerations, possible design rules for the preparation of future MO-active composites will also be discussed along with fundamental aspects of polymer/nanoparticle systems engineering.

 

 

Biography


Nicholas Pavlopoulos completed his undergraduate degree in Chemistry, Economics, and Finance at North Central College in central Illinois, during which time he worked as a R&D Chemist at Nanophase Technologies Corporation, developing commercial nanomaterial dispersions for polishing, cosmetic, coating, and battery applications. After this, he went on to earn his PhD from the University of Arizona, where he studied polymer and nanomaterial chemistry under Professor Jeffrey Pyun. During his time at the University of Arizona, Dr. Pavlopoulos studied a variety of polymer/nanomaterial analogues and composites to expand fundamental understandings of colloidal polymer systems, developed new sulfur-polymer composites for use in Li-S batteries/energy storage, and explored structure-property relationships in energetically relevant metal-functionalized II-VI semiconductor nanomaterial systems. Subsequently, he accepted a position as a Research Scientist in the College of Optical Sciences at the University of Arizona, working as a team leader on developing all-optical magnetometers and hybrid organic/inorganic optical isolators under Professor Robert Norwood. In January 2019, Nicholas began working at Technion - Israel Institute of Technology in Haifa, Israel with Associate Professor Lilac Amirav as a Marie-Sklodowska Curie Individual Fellow under the Horizon 2020 EU Funding action. His current research interests focus on using precision nanochemistry to unravel key challenges in the use of nanomaterial systems for solar driven overall water splitting, in particular through engineering of unique structural motifs and engineering of ligand-particle interactions to favor selective co-catalyst deposition, accelerated hole-transfer rates, and enhanced catalytic activity.

 

 

"Attosecond X-ray absorption spectroscopy in condensed matter"

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"Maximising the impact of your research"

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