Magnetic structure of the noncentrosymmetric magnet Sr2MnSi2O7 through irreducible representation and magnetic space group analyses

TL;DR

This study elucidates the magnetic structure of Sr2MnSi2O7 using neutron diffraction and magnetometry, revealing field-dependent magnetic moment arrangements and refining parameters within a magnetic space group framework.

Contribution

It applies irreducible representation and magnetic space group analyses to determine the magnetic structures of Sr2MnSi2O7, highlighting field-induced changes and advancing magnetic structure refinement methods.

Findings

Magnetic moments are in-plane within the zero-field magnetic space group.

A magnetic field induces a transition to a different magnetic space group.

Refined parameters follow a recent magnetic space group framework.

Abstract

Magnetic structures of the noncentrosymmetric magnet Sr$_2$MnSi$_2$O$_7$ were examined through neutron diffraction for powder and single-crystalline samples, as well as magnetometry measurements. All allowed magnetic structures under the space group $P\bar{4}2_1 m$ with the magnetic wavevector $\vec{q}_{\rm m}=(0,0,1/2)$~r.l.u., were analysed via irreducible representation and magnetic space group approaches. The compound is refined to have in-plane magnetic moments within the magnetic space group $Cmc2_1.1^{\prime}_c$ (\#36.177) under zero field, which can be altered to $P2_1 2_1 2_1.1^{\prime}_c$ (\#19.28) above $\mu_0 H=0.067(5)$~T to align induced weak-ferromagnetic components within one layer on the $ab$-plane. All refined parameters are provided following the recent framework based upon the magnetic space group, which better conveys when exchanging crystallographic information for commensurate magnetic structures.