In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Ferromagnetic materials

http://xrm.phys.northwestern.edu/research/pdf_papers/2004/egerton_micron_2004.pdf

Radiation damage in the TEM and SEM.

http://files.janapv.webnode.cz/200000097-8a03f8afdf/ex_bias_nano.pdf

Exchange bias in nanostructures

Biocompatibility, Pharmaceutical and Biomedical Applications L. Harivardhan Reddy,†,‡ Jose ́ L. Arias, Julien Nicolas,† and Patrick Couvreur*,† †Laboratoire de Physico-Chimie, Pharmacotechnie et Biopharmacie, Universite ́ Paris-Sud XI, UMR CNRS 8612, Faculte ́ de Pharmacie, IFR 141, 5 rue Jean-Baptiste Cleḿent, F-92296 Chat̂enay-Malabry, France Departamento de Farmacia y Tecnología Farmaceútica, Facultad de Farmacia, Campus Universitario de Cartuja s/n, Universidad de Granada, 18071 Granada, Spain ‡Pharmaceutical Sciences Department, Sanofi, 13 Quai Jules Guesdes, F-94403 Vitry-sur-Seine, France

Magnetic nanoparticles: design and characterization, toxicity and biocompatibility, pharmaceutical and biomedical applications.

Transparent conductors as solar energy materials: A panoramic review

Antiphase boundaries (APBs) were observed in ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ single crystal films grown on MgO. The APBs are an intrinsic consequence of the nucleation and growth mechanism in films. Across an APB, the intrasublattice superexchange coupling is greatly strengthened, while the intersublattice superexchange coupling is weakened, reversing the dominant interaction from that found in the bulk. Thus the APB separates oppositely magnetized regions, consistent with Lorentz microscopy measurements. The APBs induce very large saturation fields and nearly random magnetization distribution in zero field.

Origin of the Anomalous Magnetic Behavior in Single Crystal Fe 3 O 4 Films

Magnetic domain structures in thin foils may be revealed in a number of ways in the transmission electron microscope. The most commonly used modes (Fresnel, Foucault, holographic, differential phase contrast and low angle diffraction) are described and intercompared. The Fresnel and Foucault modes are simple to implement but provide a mainly qualitative description of the spatial variation of induction throughout the foil. Quantitative information may be obtained from the other two imaging modes but they require more sophisticated equipment. Electron diffraction is particularly useful for studying periodic magnetic structures. Examples of the use of these, and further specialised techniques, are presented by reference to some applications of current interest within magnetism.

https://iopscience.iop.org/article/10.1088/0022-3727/17/4/003/pdf

The investigation of magnetic domain structures in thin foils by electron microscopy

The direct determination of magnetic domain wall profiles by differential phase contrast electron microscopy.

Switching fields of magnetic elements with nanometric dimensions have been investigated by Lorentz microscopy using a transmission electron microscope. Acicular elements of Co and Ni80Fe20 were fabricated by electron beam lithography and lift-off techniques. They were 1.6–3.5 μm long, 200 nm wide, and 20–50 nm thick, with flat rectangular ends or triangular pointed ends, and were patterned in linear arrays with center-to-center spacing ranging from 7 μm to 250 nm. Switching fields and reversal behavior of the elements were found to depend strongly on the shape of the ends and, in a closely packed array, on element separation, thereby providing a way of controlling their magnetic properties.

Switching fields and magnetostatic interactions of thin film magnetic nanoelements

A modification to the differential phase contrast mode of Lorentz microscopy is proposed in which an annular quadrant detector is used instead of the standard solid quadrant detector. The new imaging mode allows a high degree of control over the relative efficiencies with which low and high spatial frequency information can be transferred from the specimen to the image. This makes it possible to effect a considerable separation of contrast arising from magnetic and nonmagnetic origins in thin polycrystalline magnetic films and thus reveals finer magnetic detail than was hitherto possible. Experimental details of the implementation of the technique, together with examples of its use for investigating thin-film recording media, are presented. >

J. N. Chapman

Papers

Origin of the Anomalous Magnetic Behavior in Single Crystal Fe 3 O 4 Films

The investigation of magnetic domain structures in thin foils by electron microscopy

The direct determination of magnetic domain wall profiles by differential phase contrast electron microscopy.

Switching fields and magnetostatic interactions of thin film magnetic nanoelements

Modified differential phase contrast Lorentz microscopy for improved imaging of magnetic structures