The Verwey transition in magnetite as studied by means of definite impurity doping
-
F. Walzl
,
J. H. V. J. Brabers
Abstract
The effect of low-dose cation doping (0:005 < x < 0:08) of magnetite single crystals, Fe3–xMxO4 (M = Ni,Mg, Co, Al, Ti, Ga), has been studied by means of the magnetic after-effect (MAE) spectroscopy with respect to (i) the Verwey transition, (ii) the low-temperature (4 K < T < 125 K ≃ TV) charge transport mechanisms and (iii) the zero-crossing of the crystal anisotropy. The observed low-temperature shifting of the transition (TV) is in fair agreement with previous conductivity measurements. Variations of the MAE spectra clearly indicate the low-temperature tunnelling (4 K < T < 35 K) to be far more affected by smallest impurity doping than variable long-range hopping (50 K < T < 125 K) – this outstanding sensibility of the tunnelling processes against impurities or any other defects is also true when compared with the corresponding TV shifting. All samples undergo a doping-induced temperature splitting, ΔTVC, between the Verwey transition (spontaneous jump of the susceptibility at TV) and the zero-crossing of the crystal anisotropy (giving rise to a delayed susceptibility maximum) – in contrast to perfectly stoichiometric Fe3O4 single crystals where both effects are coincident. This range of temperature-splitting ΔTVC, found to be extremely large in the case of Co2+ doping, is characterized by destabilized magnetic domain structures due to locally disordered anisotropy distribution in the lattice.
Dedicated to Professor Dr. Helmut Kronmüller on the occasion of his 70th birthday
The authors are very grateful to Prof. Dr. H. Kronmüller for numerous fruitful and stimulating discussions over the course of many years. They highly appreciate the technical assistance of Mrs. Th. Dragon and Mrs. I. Schofron in the preparation of this manuscript.
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© 2002 Carl Hanser Verlag, München
Articles in the same Issue
- Frontmatter
- Editorial
- Editorial
- Articles/Aufsätze
- Interplay between chemical and magnetic roughness of Pt in a Pt/Co bilayer investigated with X-ray resonant magnetic reflectometry
- Thermal stability and magnetic anisotropy dispersion in high-density hard-disk media
- Thickness dependence of magnetization structures in thin Permalloy rectangles
- Solving the selectivity problem in magnetic random access memories using configurations that form C-states
- Second-order magnetoelastic effects: From the Dirac equation to the magnetic properties of ultrathin epitaxial films for magnetic thin-film applications
- Magnetic relaxation in nanocrystalline systems: linking Monte Carlo steps with time
- Effect of domain size on the magneto-elastic damping in amorphous ferromagnetic metals
- The character and role of grain boundaries in NdFeB-type alloys and magnets
- Magnetic domain structure and spin reorientation process
- Magnetic properties of Tb(Fe, Mo)12 and Tb(Fe, Mo)12C compounds
- Microstructure, magnetic properties and magnetic hardening in 2 : 17 Sm–Co magnets
- Micromagnetism and microstructure – tailoring of high-performance permanent magnets
- Metastable alloys at moderate cooling rates
- Thermal critical phenomena and crossover between critical regimes in ferromagnets with long-range interactions
- Vacancies in thermal equilibrium and ferromagnetism near the Curie temperature
- The vortex lattice in superconductors
- Functional substrates – a novel approach to tailor transport properties and flux-line pinning in YBa2Cu3O7 – x thin films
- Superconducting permanent magnets and their application in magnetic levitation
- Magneto-optical studies of flux pinning in high-temperature superconductors
- Atomic transport in amorphous metals
- A novel technique for measuring diffusivities of short-lived radioisotopes in solids
- Hydrogen four-level tunnel systems in substitutional body-centred cubic alloys
- Magnetic relaxation phenomena in cobalt
- The Verwey transition in magnetite as studied by means of definite impurity doping
- Notifications/Mitteilungen
- Personal/Personelles
- Bücher/Books
- Conferences/Konferenzen
- DGM Training/DGM Fortbildung
Articles in the same Issue
- Frontmatter
- Editorial
- Editorial
- Articles/Aufsätze
- Interplay between chemical and magnetic roughness of Pt in a Pt/Co bilayer investigated with X-ray resonant magnetic reflectometry
- Thermal stability and magnetic anisotropy dispersion in high-density hard-disk media
- Thickness dependence of magnetization structures in thin Permalloy rectangles
- Solving the selectivity problem in magnetic random access memories using configurations that form C-states
- Second-order magnetoelastic effects: From the Dirac equation to the magnetic properties of ultrathin epitaxial films for magnetic thin-film applications
- Magnetic relaxation in nanocrystalline systems: linking Monte Carlo steps with time
- Effect of domain size on the magneto-elastic damping in amorphous ferromagnetic metals
- The character and role of grain boundaries in NdFeB-type alloys and magnets
- Magnetic domain structure and spin reorientation process
- Magnetic properties of Tb(Fe, Mo)12 and Tb(Fe, Mo)12C compounds
- Microstructure, magnetic properties and magnetic hardening in 2 : 17 Sm–Co magnets
- Micromagnetism and microstructure – tailoring of high-performance permanent magnets
- Metastable alloys at moderate cooling rates
- Thermal critical phenomena and crossover between critical regimes in ferromagnets with long-range interactions
- Vacancies in thermal equilibrium and ferromagnetism near the Curie temperature
- The vortex lattice in superconductors
- Functional substrates – a novel approach to tailor transport properties and flux-line pinning in YBa2Cu3O7 – x thin films
- Superconducting permanent magnets and their application in magnetic levitation
- Magneto-optical studies of flux pinning in high-temperature superconductors
- Atomic transport in amorphous metals
- A novel technique for measuring diffusivities of short-lived radioisotopes in solids
- Hydrogen four-level tunnel systems in substitutional body-centred cubic alloys
- Magnetic relaxation phenomena in cobalt
- The Verwey transition in magnetite as studied by means of definite impurity doping
- Notifications/Mitteilungen
- Personal/Personelles
- Bücher/Books
- Conferences/Konferenzen
- DGM Training/DGM Fortbildung
