  We report a device fabrication strategy of making multi-terminal electrical
contacts on small (< 1 mm) bulk quantum materials using lithography-based
techniques for electrical transport studies. The crystals are embedded in a
polymeric medium to planarize the top surface, and then standard lithography
and microfabrication techniques are directly applied to form electrodes with
various geometries. This approach overcomes the limitations of crystal
thickness and lateral dimensions on establishing electrical contacts. We use
low stress polymers to minimize the extrinsic thermal strain effect at low
temperatures, which allow reliable transport measurements on quantum materials
that are sensitive to strain. The crystal surface planarization method has
enabled electronic transport studies such as in-plane anisotropy, Hall
measurements on small, bulk BaTiS3 (BTS) crystals, and provides unique
opportunities for two-dimensional (2D) heterogeneous integration on
three-dimensional (3D) / quasi-one-dimensional (quasi-1D) bulk materials. Our
strategy is general for many small, non-exfoliable crystals of newly
synthesized quantum materials and paves the way for performing versatile
transport studies on those novel materials.
