"Novel Properties of Topologically Interesting Materials and their Simple Devices" by Dr.Mazhar Ali from Max Plack institute

Wednesday, March 21, 2018 - 4:00pm
Condensed Matter Physics Seminar

"TI, Dirac, Weyl, and Nodal Line materials are all members of the burgeoning basket of topological materials where physical properties, like electron transport) are strongly influenced by the topology of the electronic structure. This can manifest in non massive-Dirac-Fermion quasiparticles in the bulk and on the surface/edges of the crystal. While many properties have been explored, especially in the bulk, novel properties of these materials may still be discovered in the ultrathin limit, especially when fabricated in heterostructures which add inversion symmetry breaking and/or magnetism to the stack. Some of these can be very important for technological applications.

Here I will discuss several directions of research being carried out by my group on topological or "nearly" topological materials. First we set out to understand why Beta-W, like Pt, has one of the largest Spin Hall Effects (SHE) known and from that understanding we realize that materials with a large SHE are not uncommon and develop a design strategy to find new materials with that trait. Experimental verification is jow underway. Secondly, we will discuss the Aymmetric Josephson Effect; the non-sinusoidal dependance of the current versus phase relationship we find in Josephson Junctions we fabricated out of WTe2 (a type II Weyl semimetal). Finally we will discuss the surprising saturation of resistivity at low temperature ( < 100K ) we found in quantum spin liquid candidate Nb3Cl8, and its dependance on charge injection via gating."

PAB 4-330