Thermal Hall effect from topological magnon-polarons
Dr Harley Scammell, Research Fellow, UNSW
We consider the puzzle of the large thermal Hall effect observed recently in the undoped cuprates. It is well established that if the heat carriers of the system host a topological band structure, then they will induce a thermal Hall effect. However, the undoped cuprate is treated as alayered two-dimensional, square-lattice quantum antiferromagnet, with no inherent topological band structure for the magnons or phonons — which are the only two sensible heat carriers in the game. In this work, we derive a linear coupling between magnons and phonons, which generates a hybridisation, and show that the hybrid magnon-phonon (i.e. magnon-polaron) hosts a topological band structure. From here we use the established reasoning to argue that the measured thermal Hall effect is a manifestation of the topological edge current.
About the presenter
Dr Harley Scammell is a postdoctoral researcher working with Prof Oleg Sushkov at UNSW on the theory of artificial graphene in FLEET’s Research Theme 1, topological materials.
Dr Scammell’s research focusses on the interplay of various tuning parameters – such as strain and spin-orbit coupling – on the electronic properties of artificial graphene. Key considerations are additional, emergent Dirac points and topological insulator phases.
