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Free keywords:
Neutron powder diffraction, Specific heat of solids, Strain measurement, Thermography (temperature measurement), Antiperovskite, Magnetic-phase transition, Magnetoelectrics, Neutron powder diffraction data, Noncollinear magnetic structures, Powder neutron diffraction, Property, Rietveld analyzes, Specific heat measurement, Spin arrangement, Rietveld analysis
Abstract:
We present the magnetic properties of the chiral, polar, and possibly magnetoelectric antiperovskite β-Fe2SeO as derived from magnetization and specific-heat measurements as well as from powder neutron diffraction and Mössbauer experiments. Our macroscopic data unambiguously reveal two magnetic phase transitions at TN1 ≈ 103 K and TN2 ≈ 78 K, while Rietveld analysis of neutron powder diffraction data reveals a noncollinear antiferromagnetic structure featuring magnetic moments in the a-b plane of the trigonal structure and a ferromagnetic moment along c. The latter is allowed by symmetry between TN1 and TN2, weakly visible in the magnetization data yet unresolvable microscopically. While the intermediate phase can be expressed in the trigonal magnetic space group P31, the magnetic ground state is modulated by a propagation vector q = (1/2 1/2 0) resulting in triclinic symmetry and an even more complex low-temperature spin arrangement which is also reflected in the Mössbauer hyperfine patterns indicating additional splitting of Fe sites below TN2. The complex noncollinear spin arrangements suggest interesting magnetoelectric properties of this polar magnet. © 2024 American Chemical Society.
