# Antiferromagnetic Stacking of Ferromagnetic Layers and Doping Controlled Phase Competition in Ca$_{1-x}$Sr$_{x}$Co$_{2-y}$As$_{2}$

## TL;DR

This study investigates the magnetic phase transitions in Ca$_{1-x}$Sr$_{x}$Co$_{2-y}$As$_{2}$, revealing a complex interplay of 1D magnetic frustration, stacking variations, and doping effects through neutron diffraction and theoretical modeling.

## Contribution

It uncovers the role of 1D magnetic frustration and stacking variations in the magnetic phase diagram of Ca$_{1-x}$Sr$_{x}$Co$_{2-y}$As$_{2}$, combining experimental data with classical analytical calculations.

## Key findings

- Identification of x-dependent magnetic transitions.
- Evidence for 1D magnetic frustration between layers.
- Explanation of magnetic order changes via a 1D Heisenberg model.

## Abstract

In search of a quantum phase transition between the two-dimensional ($2$D) ferromagnetism of CaCo$_{2-y}$As$_{2}$ and stripe-type antiferromagnetism in SrCo$_{2}$As$_{2}$, we rather find evidence for $1$D magnetic frustration between magnetic square Co layers. We present neutron diffraction data for Ca$_{1-x}$Sr$_{x}$Co$_{2-y}$As$_{2}$ that reveal a sequence of $x$-dependent magnetic transitions which involve different stacking of $2$D ferromagnetically-aligned layers with different magnetic anisotropy. We explain the $x$-dependent changes to the magnetic order by utilizing classical analytical calculations of a $1$D Heisenberg model where single-ion magnetic anisotropy and frustration of antiferromagnetic nearest- and next-nearest-layer exchange are all composition dependent.