Strong magnetoresistance in a graphene Corbino disk at low magnetic fields

Abstract

In the Hall bar geometry, both the transverse and longitudinal bulk conductivities -- ${\ensuremath{\sigma}}_{x\phantom{\rule{0}{0ex}}y}(B)$ and ${\ensuremath{\sigma}}_{x\phantom{\rule{0}{0ex}}x}(B)$, respectively -- determine the resistivity ${\ensuremath{\rho}}_{x\phantom{\rule{0}{0ex}}x}(B)$. Consequently, magnetoresistance $R(B)$ becomes independent of the applied magnetic field $B$ in the simplest one-band model. In the corresponding Corbino-ring setting, ${\ensuremath{\sigma}}_{x\phantom{\rule{0}{0ex}}y}$ drops out and the resistivity is obtained as ${\ensuremath{\rho}}_{x\phantom{\rule{0}{0ex}}x}(B)=1/{\ensuremath{\sigma}}_{x\phantom{\rule{0}{0ex}}x}(B)$. Strong, pure ${B}^{2}$ magnetoresistance is observed in the reported experimental work and used to extract information about scattering mechanisms in graphene, which amply demonstrates the usefulness of the Corbino-ring geometry for transport studies of 2D materials.