An overview of the self-organizing map algorithm, on which the papers in this issue are based, is presented in this article.

The Self-Organizing Map

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

Multiferroic magnetoelectric composite systems such as ferromagnetic-ferroelectric heterostructures have recently attracted an ever-increasing interest and provoked a great number of research activities, driven by profound physics from coupling between ferroelectric and magnetic orders, as well as potential applications in novel multifunctional devices, such as sensors, transducers, memories, and spintronics. In this Review, we try to summarize what remarkable progress in multiferroic magnetoelectric composite systems has been achieved in most recent few years, with emphasis on thin films; and to describe unsolved issues and new device applications which can be controlled both electrically and magnetically.

Recent Progress in Multiferroic Magnetoelectric Composites: from Bulk to Thin Films

In the past decade, the surface plasmon resonance of Ag and Au nanoparticles has been investigated to improve the efficiency of photocatalytic processes. The photocatalytic production of fuels is particularly interesting for its ability to store the sun's energy in chemical bonds that can be released later without producing harmful byproducts. This Feature Article reviews recent work demonstrating plasmon-enhanced photocatalytic water splitting, reduction of CO2 with H2O to form hydrocarbon fuels, and degradation of organic molecules. Focus is placed on several possible mechanisms that have been previously discussed in the literature. A particular emphasis is given to several aspects of these mechanisms that are not fully understood and will require further investigation.

A Review of Surface Plasmon Resonance‐Enhanced Photocatalysis

http://www2.physics.colostate.edu/groups/WuGroup/publications/MMM_2009_Recent%20advances%20in%20processing%20and%20applications%20of%20microwave%20ferrites.pdf

Recent advances in processing and applications of microwave ferrites

We demonstrate a semiconducting material, TiO2??, with ferromagnetism up to 880?K, without the introduction of magnetic ions. The magnetism in these films stems from the controlled introduction of anion defects from both the film?substrate interface as well as processing under an oxygen-deficient atmosphere. The room-temperature carriers are n-type with n~3 ? 1017?cm?3. The density of spins is ~1021?cm?3. Magnetism scales with conductivity, suggesting that a double exchange interaction is active. This represents a new approach in the design and refinement of magnetic semiconductor materials for spintronics device applications.

https://iopscience.iop.org/article/10.1088/0953-8984/18/27/L01/pdf

Oxygen-defect-induced magnetism to 880 K in semiconducting anatase TiO2−δ films

Next generation magnetic microwave devices require ferrite films to be thick (>300μm), self-biased (high remanent magnetization), and low loss in the microwave and millimeter wave bands Here we examine recent advances in the processing of thick Ba-hexaferrite (M-type) films using pulsed laser deposition (PLD), liquid-phase epitaxy, and screen printing These techniques are compared and contrasted as to their suitability for microwave materials processing and industrial production Recent advances include the PLD growth of BaM on wide-band-gap semiconductor substrates and the development of thick, self-biased, low-loss BaM films by screen printing

Ba-hexaferrite films for next generation microwave devices (invited)

A series of (Fe100−yGay)1−xBx (x=0–21 and y=9–17) films were deposited; their microstructure, soft magnetism, magnetostrictive behavior, and microwave properties were investigated. The addition of B changes the FeGaB films from polycrystalline to amorphous phase and leads to excellent magnetic softness with coercivity <1Oe, high 4πMs, self-biased ferromagnetic resonance (FMR) frequency of 1.85GHz, narrow FMR linewidth (X band) of 16–20Oe, and a high saturation magnetostriction constant of 70ppm. The combination of these properties makes the FeGaB films potential candidates for tunable magnetoelectric microwave devices and other rf/microwave magnetic device applications.

https://repository.library.northeastern.edu/files/neu:329824/fulltext.pdf

Soft magnetism, magnetostriction, and microwave properties of FeGaB thin films

Cold atmospheric plasma (CAP) surface nanomodified 3D printed polylactic acid (PLA) scaffolds for bone regeneration

Strong magnetoelectric (ME) coupling was demonstrated in Fe3O4/PZN–PT (lead zinc niobate–lead titanate) multiferroic heterostructures obtained through a sputter deposition process. The dependence of the magnetic anisotropy on the electric field (E-field) is theoretically predicted and experimentally observed by ferromagnetic resonance spectroscopy. A large tunable in-plane magnetic anisotropy of up to 600 Oe, and tunable out-of-plane anisotropy of up to 400 Oe were observed in the Fe3O4/PZN–PT multiferroic heterostructures, corresponding to a large ME coefficient of 100 Oe cm/kV in plane and 68 Oe cm/kV out of plane, which match well with predicted results. In addition, the electric field manipulation of magnetic anisotropy is also demonstrated by the electric fields dependence of magnetic hysteresis loops, showing a large squareness ratio change of 44%. These Fe3O4/PZN–PT multiferroic heterostructures exhibiting large E-field tunable magnetic properties provide great opportunities for novel electrostatic...

https://repository.library.northeastern.edu/files/neu:329794/fulltext.pdf

Katherine S. Ziemer

Papers

Oxygen-defect-induced magnetism to 880 K in semiconducting anatase TiO2−δ films

Ba-hexaferrite films for next generation microwave devices (invited)

Soft magnetism, magnetostriction, and microwave properties of FeGaB thin films

Cold atmospheric plasma (CAP) surface nanomodified 3D printed polylactic acid (PLA) scaffolds for bone regeneration

Electrical tuning of magnetism in Fe3O4/PZN-PT multiferroic heterostructures derived by reactive magnetron sputtering