Research Interests

Topological Materials

After coming to Caltech, I developed an interest in topological materials. The recent (2006) discovery of the so-called “symmetry protected topological (SPT) phases” known as topological insulators has resulted in a great deal of activity in the condensed matter physics community. Due to the amount of attention this subject is receiving these days, I was able to appreciate the importance of topological phases discovered almost 3 decades ago, namely the integer and fractional quantum Hall effects. What’s even more interesting about topologically nontrivial systems is that they are not limited to any subfield of physics. In addition to condensed matter physics, they can potentially be realized even in photonics, AMO physics, and (obviously) certain high-energy phenomena. I am currently interested in learning more about exotic topological quantum phases as well as witnessing the revision of concepts and definitions, used for the classification of condensed matter phases, which will take into account the new physical insights we gain from these exotic topological phases.

Exotic Strongly-Correlated Phases

Surprisingly, I was exposed to certain interesting areas of condensed matter physics, such as superconductivity, magnetism, strongly-correlated systems, high-temperature superconductivity, heavy fermion materials, etc., as I started learning some of the work being done in topological materials! It’s astonishing that, despite growth and characterization having reached atomic precision, the understanding of these exotic phases is still limited. In accordance with the principle of “emergence,” it’s hard (almost impossible) to answer the question: “How much more do we need to learn to say that we understand “all” of condensed matter physics?” I am excited and grateful, beyond words, to be one of the countless researchers participating in this quest to chart out the phase diagram of condensed matter physics.

Graphene

Graphene device on Silicon Nitride subtrate

During almost all of my research projects in my undergrad, I have worked extensively on understanding graphene from a fundamental as well as practical point of view. My work on graphene has primarily involved studying the effects of different substrates on its electronic properties. I was primarily interested in polymers due to their hydrophobicity. I have investigated two substrates: the inorganic dielectric Silicon Nitride (Si3N4) and the ferroelectric polymer poly[(vinylidenefluoride-co-trifluoroethylene] or P(VDF-TrFE). At first, I got interested in P(VDF-TrFE) mainly due to its hydrophobicity; but once I learned of its interesting properties, namely ferroelectricity, pyroelectricity, and piezoelectricity, I was overwhelmed with ideas of many cool graphene devices that can be fabricated with P(VDF-TrFE) as the substrate. I also studied the microscopic charge transfer mechanisms between graphene and a thin (10 nm) Si3N4 substrate by quantifying, under different conditions, the hysteresis effect on transport properties of back-gated graphene field-effect devices (see publications section below).

 

Publications

S. A. Imam, T. Deshpande, A. Guermoune, M. Siaj, and T. Szkopek, “Charge transfer hysteresis in graphene dual-dielectric memory cell structures,” Appl. Phys. Lett. 99, 082109 (2011)