The Electronic and Magnetic Properties of Magnetoresistant Nd1-xSrxMnAsO Oxyarsenides

TL;DR

This study investigates how doping Nd1-xSrxMnAsO with strontium affects its crystal structure, magnetic order, and magnetoresistance, revealing preserved antiferromagnetic order and the emergence of metallic behavior and positive magnetoresistance.

Contribution

It provides new insights into the structural, magnetic, and electronic changes in Nd1-xSrxMnAsO oxypnictides due to Sr doping, including the preservation of magnetic order and magnetoresistance mechanisms.

Findings

No change in crystal symmetry with Sr doping.

Inter-layer distance increases with x.

Metallic behavior emerges for x > 0.05.

Abstract

The oxypnictides Nd1-xSrxMnAsO have been successfully synthesised with x up to 0.1. A synchrotron X-ray diffraction study demonstrates that there is no change in crystal symmetry upon doping with Sr. An expansion of the inter-layer distance between Nd-O-Nd and As-Mn-As blocks is observed with increasing x. Results from variable temperature neutron diffraction and resistivity measurements show that the local moment antiferromagnetic order of the Mn spins is preserved as the [MnAs]- layers are hole doped and the materials are driven metallic for x > 0.05. A sizeable positive magnetoresistance is observed at low temperature which demonstrates that multiple MR mechanisms are possible in LnMnAsO oxypnictides.