There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The recent literature concerning the magnetocaloric effect (MCE) has been reviewed. The MCE properties have been compiled and correlations have been made comparing the behaviours of the different families of magnetic materials which exhibit large or unusual MCE values. These families include: the lanthanide (R) Laves phases (RM2, where M = Al, Co and Ni), Gd5(Si1−xGex)4 ,M n(As1−xSbx), MnFe(P1−xAsx), La(Fe13−xSix) and their hydrides and the manganites (R1−xMxMnO3, where R = lanthanide and M = Ca, Sr and Ba). The potential for use of these materials in magnetic refrigeration is discussed, including a comparison with Gd as a near room temperature active magnetic regenerator material. (Some figures in this article are in colour only in the electronic version)

https://iopscience.iop.org/article/10.1088/0034-4885/68/6/R04/pdf

Recent developments in magnetocaloric materials

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

Surface plasmons (SPs) are coherent oscillations of conduction electrons on a metal surface excited by electromagnetic radiation at a metal -dielectric interface. The growing field of research on such light -metal interactions is known as ‘plasmonics’. 1-3 This branch of research has attracted much attention due to its potential applications in miniaturized optical devices, sensors, and photonic circuits as well as in medical diagnostics and therapeutics. 4-8

Nanostructured plasmonic sensors.

Review of the magnetocaloric effect in manganite materials

The effects on the ferromagnetism of a nitrogen defect in Cu-doped AlN with a Cu concentration of 2.77-8.33% have been investigated by first-principles. For AI0.9723Cu0.0277N, a global magnetic moment of 1.46 μB/cell with a localized magnetic moment of 0.75 μB/Cu is found. The formation of Cu-Cu in AlN with the N vacancy (VN) is more energetically favorable than that without the VN. Hence, the Cu + VN state is produced easily. The Cu magnetic moment of Cu-Cu pair becomes very low by the weak 3d-3d spin coupling due to the spin-exchange interaction between Cu-3d and N defect states.

Nitrogen Vacancy and Magnetic Property in Cu-Doped AlN From First-Principles Calculations

We suggest a patterned ferromagnetic multibits element for an ultrahigh density magnetic recording media. The pattern is composed of a circular ferromagnetic disk in contact to four needle-shaped sharp equilateral triangles. By using micromagnetic simulation, we found that a spin configuration of circular ferromagnetic disk is modified with position of magnetic vortex core shifted from the center by selecting a specific combination of spin states of four needles. We explore the possibility of multibits recording by shifting magnetic vortex core position in the ferromagnetic element.

Multibits magnetic recording using a ferromagnetic element with shifted vortex core position

The effect of lattice structure on the magnetic and transport properties of La0.7Ca0.3-xSrxMnO3 (x= 0; 0.03; 0.06; ...; 0.3) lanthanum manganites have been studied. Curie temperature pressure coeff ...

Seong-Cho Yu

Papers

Nitrogen Vacancy and Magnetic Property in Cu-Doped AlN From First-Principles Calculations

Multibits magnetic recording using a ferromagnetic element with shifted vortex core position

La0.7Ca0.3-xSrxMnO3 Manganites: Effect of Structure on the Magnetic and Transport Properties.

Large magnetic entropy change above 300 K in manganites

Ti-doped A-site deficient lanthanum manganites: Local structure and properties