A model for magnetoresistance in thin films using local topographic characterization data

Thin-film quantum materials often show electrical transport signatures - like linear magnetoresistance - that are attributed to novel phenomena. However, there can be many alternative explanations for these transport signatures, such as local inhomogeneity or disorder effects. Parish and Littlewood (Nature 426, 162 (2003)) and subsequent researchers studied one model for electrical transport in the presence of disorder that can also give rise to a linear magnetoresistance. Researchers often discuss this model as an alternative explanation for linear magnetoresistance, but typically do not generate quantitative predictions or assess its suitability using local materials characterization data. We have implemented and tested an extension of the Parish and Littlewood model that uses scanning probe height maps as a proxy for local conductance. Our approach predicts local voltage and current transport throughout a material, shows good agreement with scanning potentiometry studies of graphene, and can be used to quantitatively assess disorder-based explanations for linear magnetoresistance and related effects.