# A case study of bilayered spin-$1/2$ square lattice compound [VO(HCOO)$_2\cdot$(H$_2$O)]

## TL;DR

This study synthesizes and characterizes a bilayered spin-1/2 square lattice compound, revealing its quasi-two-dimensional magnetic behavior, antiferromagnetic ordering at low temperature, and structural details via various experimental techniques.

## Contribution

It provides a comprehensive structural and magnetic analysis of [VO(HCOO)$_2 ext{·}$(H$_2$O)] using multiple experimental methods, highlighting its quasi-2D magnetic properties and anisotropy.

## Key findings

- Quasi-two-dimensional magnetic behavior confirmed.
- Antiferromagnetic ordering at approximately 1.1 K.
- Strong in-plane magnetic anisotropy observed.

## Abstract

We present the synthesis and a detail investigation of structural and magnetic properties of polycrystalline [VO(HCOO)$_2\cdot$(H$_2$O)] by means of x-ray diffraction, magnetic susceptibility, high-field magnetization, heat capacity, and electron spin resonance measurements. It crystallizes in a orthorhombic structure with space group $Pcca$. It features distorted VO$_6$ octahedra connected via HCOO linker (formate anions) forming a two-dimensional square lattice network with a bilayered structure. Analysis of magnetic susceptibility, high field magnetization, and heat capacity data in terms of the frustrated square lattice model unambiguously establish quasi-two-dimensional nature of the compound with nearest neighbour interaction $J_1/k_{\rm B} \simeq 11.7$~K and next-nearest-neighbour interaction $J_2/k_{\rm B} \simeq 0.02$~K. It undergoes a N\'eel antiferromagnetic ordering at $T_{\rm N} \simeq 1.1$~K. The ratio $\theta_{\rm CW}/T_{\rm N} \simeq 10.9$ reflects excellent two-dimensionality of the spin-lattice in the compound. A strong in-plane anisotropy is inferred from the linear increase of $T_{\rm N}$ with magnetic field, consistent with the structural data.