Magnetotransport in La(Fe,Ru)AsO as a probe of band structure and mobility

TL;DR

This study investigates the magnetotransport properties of Ru-substituted LaFeAsO, revealing electron-dominated transport, Dirac cone features, high low-temperature mobility, and weak disorder effects, with implications for understanding superconductivity mechanisms.

Contribution

The paper provides detailed experimental and theoretical analysis of band structure and mobility in La(Fe,Ru)AsO, highlighting Dirac cones and their impact on transport properties.

Findings

Transport dominated by electron bands

Presence of anisotropic Dirac cones confirmed by calculations

High low-temperature mobility up to 18.6 m^2/(Vs)

Abstract

In this work we investigate the Ru substituted LaFeAsO compound, by studying the magnetotransport behaviour and its relationship with the band structure, in different regimes of temperature, magnetic field and Ru content. In particular we analyse the magnetoresistance of LaFe1-xRuxAsO (0 <= x <= 0.6) samples with the support of ab initio calculations and we find out that in the whole series: (i) the transport is dominated by electron bands only; (ii) the magnetoresistance exhibits distinctive features related to the presence of Dirac cones; indeed, ab initio calculations confirm the presence of anisotropic Dirac cones in the band structure; (iii) the low temperature mobility is exceptionally high and reaches 18.6 m2/(Vs) in the Ru-free sample at T=2K, in the extreme limit of a single Landau level occupied in the Dirac cones; (iv) the mobility drops abruptly above 10K-15K; (v) the disorder has a very weak effect on the band mobilities and on the transport properties; (vi) there exists a correlation between the temperature ranges of Dirac cones and SDW carrier condensation. These findings may be of crucial importance in the investigation of the pairing mechanism in the F-doped superconducting La(Fe,Ru)As(O,F) compounds related to this series of parent compounds.