Ba{0.4}Rb{0.6}Mn2As2: A Prototype Half-Metallic Ferromagnet

TL;DR

This study reports the discovery of half-metallic ferromagnetism in Ba0.39Rb0.61Mn2As2, demonstrating a strong link between electronic transport and magnetic properties, with potential implications for spintronic applications.

Contribution

It introduces Ba0.39Rb0.61Mn2As2 as a prototype half-metallic ferromagnet with unique magnetic and transport characteristics, expanding the understanding of doped manganese arsenides.

Findings

Complete polarization of itinerant magnetic moments at low temperature.

Resistivity follows an activated-T^2 model below Curie temperature.

Strong correlation between electronic transport and magnetic properties.

Abstract

Half-metallic ferromagnetism (FM) in single-crystal Ba{0.39(1)}Rb{0.61(1)}Mn2As2 below its Curie temperature TC = 103(2) K is reported. The magnetization M versus applied magnetic field H isotherm data at 1.8 K show complete polarization of the itinerant doped-hole magnetic moments that are introduced by substituting Rb for Ba. The material exhibits extremely soft FM, with unobservably small remanent magnetization and coercive field. Surprisingly, and contrary to typical itinerant FMs, the M(H) data follow the Arrott-plot paradigm that is based on a mean-field theory of local-moment FMs. The in-plane electrical resistivity data are fitted well by an activated-T^2 expression for T < TC, whereas the data sharply deviate from this model for T > TC. Hence the activated-T^2 resistivity model is an excellent diagnostic for determining the onset of half-metallic FM in this compound, which in turn demonstrates the presence of a strong correlation between the electronic transport and magnetic properties of the material. Together with previous data on 40% hole-doped Ba{0.6}K{0.4}Mn2As2, these measurements establish 61%-doped Ba{0.39}Rb{0.61}Mn2As2 as a prototype for a new class of half-metallic ferromagnets in which all the itinerant carriers in the material are ferromagnetic.