Metamagnetic transition in Ca$_{1-x}$Sr$_x$Co$_2$As$_2$($x$ = 0 and 0.1) single crystals

TL;DR

This study investigates the magnetic and transport properties of CaCo2As2 and Sr-doped CaCo2As2 single crystals, revealing metamagnetic transitions and proposing an A-type antiferromagnetic order with field-dependent spin polarization behaviors.

Contribution

It provides the first detailed analysis of metamagnetic transitions and magnetic ordering in CaCo2As2 and Sr-doped variants, highlighting field-induced polarization effects.

Findings

Metamagnetic transition occurs at low fields along c-axis.

Spins can be fully polarized along ab-plane in Sr-doped sample.

Proposed A-type antiferromagnetic order with ferromagnetic planes stacked antiferromagnetically.

Abstract

We report the magnetism and transport measurements of CaCo$_2$As$_2$ and Ca$_{0.9}$Sr$_{0.1}$Co$_2$As$_2$ single crystals. Antiferromagnetic transition was observed at about 70 K and 90 K for CaCo$_2$As$_2$ and Ca$_{0.9}$Sr$_{0.1}$Co$_2$As$_2$, respectively. Magnetism and magnetoresistance measurements reveal metamagnetic transition from an antiferromagnetic state to a ferromagnetic state with the critical field of 3.5 T and 1.5 T respectively along c-axis for these two materials at low temperature. For the field along ab-plane, spins can also be fully polarized above the field of 4.5 T for Ca$_{0.9}$Sr$_{0.1}$Co$_2$As$_2$. While for CaCo$_2$As$_2$, spins can not be fully polarized up to 7 T. We proposed the cobalt moments of these two materials should be ordered ferromagnetically within the ab-plane but antiferromagnetically along the c-axis(A-type AFM).