Microscopic origin of linear positive magnetoresistance

Determine the microscopic origin of linear positive magnetoresistance across topological and magnetic materials, including whether the large non-saturating linear magnetoresistance observed in MnP is governed by Abrikosov’s quantum-limit mechanism rather than classical mobility fluctuations or electron–hole compensation.

Background

The paper investigates a large, non-saturating linear positive magnetoresistance in helimagnetic MnP, particularly in its field-polarized FM2 phase. It compares three proposed mechanisms: the classical Parish–Littlewood model based on mobility inhomogeneity, nearly compensated electron–hole transport, and Abrikosov’s quantum linear magnetoresistance arising when carriers occupy the lowest Landau level.

The authors argue that the high crystal quality and hole-dominated Hall response disfavor the first two mechanisms. Their first-principles calculations identify a small Fermi pocket associated with a semi-Dirac-like crossing near the Y point, and their estimated critical fields suggest that the FM2 phase can reach the extreme quantum limit. However, the wording that the origin remains an open question indicates that the microscopic explanation is not presented as conclusively established.