Video Experimental Relacionado
Updated: Jun 3, 2026
09:06
Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
Las transiciones estructurales, magnéticas y de transporte inducidas por la presión en la escalera de dos patas
Takafumi Yamamoto1, Cédric Tassel, Yoji Kobayashi
1Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University , Kyoto 615-8510, Japan.
Journal of the American Chemical Society
|March 29, 2011
Resumen
La presión induce cambios significativos en el Sr(3)Fe(2)O(5), incluidas las transiciones estructurales, de estado de espín y magnéticas. Estos hallazgos sugieren un comportamiento general para los compuestos en capas basados en hierro relacionados bajo presión.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Física de la materia condensada Física de la materia condensada
- Química del estado sólido.
Sus antecedentes:
- Los compuestos de hierro en capas con motivos planos cuadrados de FeO4 exhiben propiedades electrónicas y magnéticas únicas.
- SrFeO(2) muestra el estado de giro inducido por la presión, el aislante al metal y las transiciones magnéticas.
Objetivo del estudio:
- Investigar el efecto de la presión sobre las propiedades estructurales, magnéticas y de transporte del Sr(3)Fe(2)O(5).
- Determine si el Sr(3)Fe(2)O(5) exhibe transiciones inducidas por la presión similares a las del SrFeO(2).
- Explorar la generalidad de las transiciones de estado de espín en compuestos en capas basados en hierro relacionados.
Principales métodos:
- Experimentos de alta presión utilizando la difracción de rayos X de sincrotrón.
- Mediciones de la susceptibilidad magnética bajo presión.
- Medidas de la resistividad eléctrica bajo presión.
Principales resultados:
- Se observó una transición estructural de la simetría Immm a Ammm a 30 ± 2 GPa.
- Una transición del estado de espín de S=2 a S=1, junto con una transición de antiferromagnético a ferromagnético, se produjo a 34 ± 2 GPa.
- La evidencia de una transición de aislante a metal se observó alrededor de 34 ± 2 GPa.
Conclusiones:
- El Sr(3)Fe(2)O(5) sufre transiciones estructurales, de estado de giro y magnéticas inducidas por la presión similares a las del SrFeO(2).
- La transición estructural parece ser independiente del estado de giro y las transiciones magnéticas.
- Estos resultados sugieren un mecanismo general para las transiciones inducidas por la presión en la serie Sr{n+1) Fe{n) O{2n+1).
Videos de Conceptos Relacionados
03:02Colors and Magnetism
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 eye.
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 eye.
01:31Ferromagnetism
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...
01:27Lattice Energies of Ionic Crystals
Lattice energy represents the energy released when gaseous cations and anions combine to form an ionic solid, reflecting the strength of electrostatic interactions within the crystal. This process is fundamentally governed by Coulombic attraction between oppositely charged ions, where the potential energy varies inversely with the interionic distance and directly with the product of ionic charges. As ions approach one another, the electrostatic energy becomes increasingly negative, indicating a...
02:42Valence Bond Theory
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...
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...
01:30Ladder Diagrams: Redox Equilibria
Ladder diagrams are useful tools for understanding redox equilibrium reactions, especially the effects of concentration changes on the electrochemical potential of the reaction. The vertical axis in the redox ladder diagrams represents the electrochemical potential, E. The area of predominance is demarcated using the Nernst equation.
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...