Honey, I Shrunk the Transport Geometry, or Carving Micro-Crystals of Topological Insulators for Transport Experiments

There exist a large number of new quantum materials that are difficult to characterize using standard electrical transport methods due to the inability to grow macroscopic crystalline samples. However, using standard TEM sample preparation methods, it is possible to carve 10s of microns size crystalline pieces and place them on an insulating substrate for transport characterization. We have demonstrated this method by carving a 2μm x 5μm x 10μm piece of SmB₆ and placing it on a Si substrate. The Hall bar was subsequently wired using Pt contacts deposited via FIB. We are also developing more demanding transport structures, such as double-sided Corbino rings with the goal of studying transport through individual threading dislocations. We will present challenges associated with sample preparation at the micro crystalline scale.