Related Experiment Video
Updated: Jun 28, 2025
09:06
Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
8.1K
Polyhedral Distortions and Unusual Magnetic Order in Spinel FeMn2O4
Qiang Zhang1,2, Wei Tian2, Roshan Nepal1
1Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
Chemistry of Materials : a Publication of the American Chemical Society
|April 15, 2024
Summary
This study reveals how polyhedral distortions in FeMn2O4 spinel influence its structural and magnetic transitions. Researchers used neutron diffraction to uncover unique noncollinear magnetic ordering driven by cation interactions.
Area of Science:
- Materials Science
- Solid State Physics
- Crystallography
Background:
- Spinel compounds (AB2X4) feature tetrahedral (AX4) and octahedral (BX6) sites, with the latter forming a geometrically frustrated pyrochlore lattice.
- Understanding the interplay between structural features and physical properties is crucial for these materials.
- FeMn2O4 is known to exhibit one structural and two magnetic transitions.
Purpose of the Study:
- To investigate polyhedral distortions and their correlation with structural and magnetic transitions in FeMn2O4.
- To elucidate the roles of A-site and B-site magnetic cations in the material's properties.
Main Methods:
- High-resolution neutron powder diffraction was employed to analyze FeMn2O4.
- Cation distribution was determined.
- Polyhedral distortions, lattice parameters, and magnetic ordering were studied across different temperatures.
Main Results:
- A cubic-tetragonal structural transition at ~750 K, driven by the Jahn-Teller effect of Mn3+ at B-sites, was observed.
- Strong magnetoelastic coupling at ~400 K indicated a collinear ferrimagnetic order with anomalies in distortions and lattice constants.
- A unique noncollinear ferrimagnetic order emerged at ~65 K, with canted spins at B2-sites and distinct magnetoelastic coupling.
Conclusions:
- FeMn2O4 exhibits distinct roles for A-site and B-site cations in its structural and magnetic behavior.
- The material serves as a platform for studying magnetic ordering and its correlation with polyhedral distortions.
- The observed noncollinear magnetic order is unique among spinel compounds.
Related Concept Videos
03:02Colors and Magnetism
11.7K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
11.7K
02:42Valence Bond Theory
8.5K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
8.5K
01:31Ferromagnetism
2.4K
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
2.4K
02:42Ionic Crystal Structures
14.3K
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
14.3K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
42.4K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
42.4K
02:58Crystal Field Theory - Octahedral Complexes
26.4K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
26.4K