Magnetic spiral order in the square-lattice spin system (CuBr)Sr$_{2}$Nb$_{3}$O$_{10}$

TL;DR

This paper demonstrates that helical magnetic order can arise in a square-lattice Heisenberg model without breaking central symmetry, exemplified by the compound (CuBr)Sr2Nb3O10, challenging conventional theories.

Contribution

It shows that quantum helical states can exist without Dzyaloshinskii-Moriya interactions, using a 2D J1-J2-J3 Heisenberg model to explain experimental observations.

Findings

Neutron experiments indicate helical spin order in (CuBr)Sr2Nb3O10.

Helical states can occur without central symmetry breaking.

The compound's properties are consistent with a 2D J1-J2-J3 Heisenberg model.

Abstract

We address quantum spin helical states in the strongly frustrated Heisenberg model. Contrary to conventional Dzyaloshinskii-Moriya approach we show that such states appear without central symmetry breaking. As an example, we demonstrate that the magnetic and thermodynamic properties of the quasi-two-dimensional square-lattice compound $\mathrm{(CuBr)Sr_{2}Nb_{3}O_{10}}$ can be interpreted within 2D $S = 1/2$ $J_1-J_2-J_3$ Heisenberg model. In this compound neutron experiment indicates helical spin order while central symmetry does hold.