Episode 3: Quantum ruler measures orbital magnetism in moiré quantum matter

In this podcast episode, MRS Bulletin’s Rahul Rao interviews Fereshte Ghahari of George Mason University about the use of a scanning tunneling microscope (STM) to measure the electronic and magnetic properties of moiré quantum materials. Ghahari and collaborators twisted two layers of graphene at a specific angle, then chilled the material to suppress as much motion as possible. They ran an STM across the material while varying the magnetic field. They could precisely observe how those field changes affected the energy levels of the electrons, realizing that they could use those discrete energy levels as a “quantum ruler.” “We hope these new measurements help researchers to optimize these magnetic and electronic properties of quantum materials for specific applications,” says Prof. Ghahari. By manipulating the electrons in moiré quantum matter and shifting its twist angles, materials researchers may be able to improve on materials that are useful for microelectronics or superconductors, for example. This work was published in a recent issue of Science.