Magnetic structure study of the sawtooth chain antiferromagnet $$\hbox {Fe}_2\hbox {Se}_2\hbox {O}_7$$ Fe 2 Se 2 O 7

Abstract

Abstract A magnetic structure of the sawtooth-chain antiferromagnet $$\hbox {Fe}_2\hbox {Se}_2\hbox {O}_7$$ Fe 2 Se 2 O 7 was investigated by magnetization measurements, single crystalline and powder neutron diffraction experiments, and a further analysis on the Mössbauer spectra. These experiments revealed a nearly collinear antiferromagnetic structure with magnetic moments aligned along the b-axis, indicating dominant antiferromagnetic exchanges between Fe(1)–Fe(2) and Fe(2)–Fe(3) sites. The magnon dispersion relation derived from the linear spin wave approximation suggests the possible flat band nature of magnons.