# Commensurate to incommensurate magnetic phase transition in Honeycomb-lattice pyrovanadate Mn2V2O7

## TL;DR

This study reports the first observation of a transition from commensurate to incommensurate magnetic order in Mn2V2O7, revealing complex magnetic phases driven by exchange interactions and spin-orbital coupling.

## Contribution

It provides the first experimental evidence of a commensurate to incommensurate magnetic phase transition in Mn2V2O7, combining neutron diffraction with magnetic measurements.

## Key findings

- Two magnetic transitions at 19 K and 11.8 K.
- Commensurate magnetic order with k1 = (0, 0.5, 0) between 11.8 K and 19 K.
- Incommensurate magnetic order with k2 = (0.38, 0.48, 0.5) below 11.8 K.

## Abstract

We have synthesized single crystalline sample of Mn$_2$V$_2$O$_7$ using floating zone technique and investigated the ground state using magnetic susceptibility, heat capacity and neutron diffraction. Our magnetic susceptibility and heat capacity reveal two successive magnetic transitions at $T_{N1} =$ 19 K and $T_{N2} =$ 11.8 K indicating two distinct magnetically ordered phases. The single crystal neutron diffraction study shows that in the temperature ($T$) range 11.8 K $\le T \le$ 19 K the magnetic structure is commensurate with propagation vector $k_1 = (0, 0.5, 0)$, while upon lowering temperature below $T_{N2} =$ 11.8 K an incommensurate magnetic order emerges with $k_2 = (0.38, 0.48, 0.5)$ and the magnetic structure can be represented by cycloidal modulation of the Mn spin in $ac-$plane. We are reporting this commensurate to incommensurate transition for the first time. We discuss the role of the magnetic exchange interactions and spin-orbital coupling on the stability of the observed magnetic phase transitions.