Carrier Tuning of Stoner Ferromagnetism in ThCr$_{\mathbf{2}}$Si$_{\mathbf{2}}$-Structure Cobalt Arsenides

TL;DR

This study investigates how hole doping in CaCo$_{2-y}$As$_2$ suppresses magnetic order by tuning the Fermi energy, demonstrating a Stoner-type transition in a frustrated itinerant magnet.

Contribution

It reveals how electronic structure tuning via hole doping can suppress magnetic order in frustrated itinerant magnets, highlighting a Stoner transition mechanism.

Findings

Magnetic order is suppressed at x≈0.25 doping level.

Fermi energy tuning away from a density of states peak causes magnetic moment quenching.

Results demonstrate a clear example of a Stoner-type transition.

Abstract

CaCo$_{2-y}$As$_2$ is an unusual itinerant magnet with signatures of extreme magnetic frustration. The conditions for establishing magnetic order in such itinerant frustrated magnets, either by reducing frustration or increasing electronic correlations, is an open question. Here we use results from inelastic neutron scattering and magnetic susceptibility measurements and density functional theory calculations to show that hole doping in Ca(Co$_{1-x}$Fe$_{x}$)$_{2-y}$As$_{2}$ suppresses magnetic order by quenching the magnetic moment while maintaining the same level of magnetic frustration. The suppression is due to tuning the Fermi energy away from a peak in the electronic density of states originating from a flat conduction band. This results in the complete elimination of the magnetic moment by $x\approx0.25$, providing a clear example of a Stoner-type transition.