Two- and three-dimensional magnetic correlations in the spin-1/2 square-lattice system Zn2VO(PO4)2

TL;DR

This study investigates magnetic correlations in Zn2VO(PO4)2, revealing long-range antiferromagnetic order below 3.75 K, coexistence of 2D short-range order and 3D order, and spin-wave excitations, advancing understanding of 2D quantum magnetism.

Contribution

The paper provides detailed neutron diffraction analysis of magnetic ordering and excitations in Zn2VO(PO4)2, highlighting coexistence of 2D and 3D magnetic correlations in a spin-1/2 square lattice system.

Findings

Long-range AFM order below 3.75 K

Pure 2D short-range AFM above TN

Presence of spin-waves confirmed by theory

Abstract

The magnetic correlations in the quasi-two dimensional spin-1/2 square-lattice system Zn2VO(PO4)2 have been investigated by neutron diffraction technique. A long-range antiferromagnetic (AFM) ordering below 3.75 K (TN) has been observed with a reduced moment of 0.66(2) {\mu}B per V ion at 1.5 K. In a given ab plane, the AFM spin arrangement is N\'eel type and the AFM layers are coupled ferromagnetically along the c axis. Remarkably, we have observed a pure 2D short-range AFM ordering in the ab plane above TN. Interestingly, the coexistence of diffuse magnetic scattering and three dimensional antiferromagnetic Bragg peaks has been found below TN, indicating the presence of spin-waves as confirmed by our calculation using the linear spin-wave theory. The observed results are discussed in the light of existing theory for a two-dimensional spin-1/2 square-lattice system.