Successive spin-flop transitions of Neel-type antiferromagnet Li$_2$MnO$_3$ single crystal with honeycomb-lattice

TL;DR

This study investigates the magnetic phase transitions of Li$_2$MnO$_3$, revealing two successive spin-flop transitions under high magnetic fields perpendicular to the honeycomb lattice, explained by a mean-field model based on neutron diffraction data.

Contribution

The paper presents the first detailed magnetic phase diagram of Li$_2$MnO$_3$ and introduces a mean-field model explaining successive spin-flop transitions in this Neel-type antiferromagnet.

Findings

Two successive meta-magnetic transitions at ~9 T for fields perpendicular to the ab-plane.

Transitions are absent when the magnetic field is applied within the ab-plane.

A mean-field model successfully explains the observed spin-flop phases.

Abstract

We have carried out high magnetic field studies of single-crystalline Li$_2$MnO$_3$, a honeycomb lattice antiferromagnet. Its magnetic phase diagram was mapped out using magnetization measurements at applied fields up to 35 T. Our results show that it undergoes two successive meta-magnetic transitions around 9 T fields applied perpendicular to the ab-plane (along the c*-axis). These phase transitions are completely absent in the magnetization measured with field applied along the ab-plane. In order to understand this magnetic phase diagram, we developed a mean-field model starting from the correct Neel-type magnetic structure, consistent with our single crystal neutron diffraction data at zero field. Our model calculations succeeded in explaining the two meta-magnetic transitions that arise when Li$_2$MnO$_3$ enters two different spin-flop phases from the zero field Neel phase.