# Suppression of magnetic order in CaCo$_{1.86}$As$_{2}$ with Fe substitution: Magnetization, neutron diffraction, and x-ray diffraction studies of Ca(Co$_{1-x}$Fe$_{x}$)$_{y}$As$_{2}$

## TL;DR

This study investigates how Fe substitution affects magnetic order in CaCo$_{1.86}$As$_{2}$, showing suppression of antiferromagnetism and structural crossover with doping, using magnetization, neutron, and x-ray diffraction techniques.

## Contribution

It provides detailed experimental insights into the suppression of magnetic order and structural transitions in Ca(Co$_{1-x}$Fe$_{x}$)$_{y}$As$_{2}$ with Fe doping, highlighting differences from steric effects.

## Key findings

- Antiferromagnetic order persists up to x≈0.12.
- Ordered moments and Néel temperature decrease linearly with x.
- No stripe or ferromagnetic order observed up to x=0.104.

## Abstract

Magnetization, neutron diffraction, and high-energy x-ray diffraction results for Sn-flux grown single-crystal samples of Ca(Co$_{1-x}$Fe$_{x}$)$_{y}$As$_{2}$, $0\leq x\leq1$, $1.86\leq y \leq 2$, are presented and reveal that A-type antiferromagnetic order, with ordered moments lying along the $c$ axis, persists for $x\lesssim0.12(1)$. The antiferromagnetic order is smoothly suppressed with increasing $x$, with both the ordered moment and N\'{e}el temperature linearly decreasing. Stripe-type antiferromagnetic order does not occur for $x\leq0.25$, nor does ferromagnetic order for $x$ up to at least $x=0.104$, and a smooth crossover from the collapsed-tetragonal (cT) phase of CaCo$_{1.86}$As$_{2}$ to the tetragonal (T) phase of CaFe$_{2}$As$_{2}$ occurs. These results suggest that hole doping CaCo$_{1.86}$As$_{2}$ has a less dramatic effect on the magnetism and structure than steric effects due to substituting Sr for Ca.