Abstract

The crystal and magnetic structures of the strong magnetoelectric BiMn2O5 have been studied as a function of pressure up to 5.7 GPa in the temperature range from 10 K to 60 K by means of neutron powder diffraction. The results reveal that the Pbam orthorhombic crystal structure remains unchanged in the investigated thermodynamic range. At ambient pressure, a long-range commensurate antiferromagnetic (AFM) phase with propagation vector q = (1/2, 0, 1/2) formed below TN = 41(2) K, accompanied by anomalies in the temperature dependence of structural parameters including the lattice parameters, interatomic distances, and bond angles. This AFM phase remained stable␣in the studied pressure range, and the relevant pressure coefficient of the Néel temperature was determined to be 3.0(4) K/GPa. No incommensurate AFM phase was detected. The magnetic properties of BiMn2O5 and their difference from most other RMn2O5 compounds were analyzed in terms of competing exchange interactions.

Keywords

Multiferroics neutron diffraction high pressure magnetic structure crystal structure 

https://doi.org/10.1007/s11664-017-5351-x