Broadband microwave electrical transport spectroscopy for two-dimensional material systems

Abstract

In recent years, interesting materials have emerged that are only available as μm-scale flakes and whose novel physics might be better understood through broadband microwave spectroscopy; examples include twisted bilayer graphene [Cao et al., Nature 556, 43 (2018)], 2D materials in which many-body phases are observed [Chen et al., Phys. Rev. Lett. 122, 026802 (2019)], and artificial lattices for analog quantum simulations [Salfi et al., Nat. Commun. 7, 1 (2016)]. Most previous techniques are unfortunately not sensitive for flakes below mm lateral sizes. We propose a simple technique that does not require sophisticated sample preparation nor Ohmic contact and show through theory and simulations that one will be able to qualitatively measure spectral features of interest and quantitatively measure the frequency-dependent complex conductivity.