다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

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

Magnetocaloric effect: From materials research to refrigeration devices

Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure. We ascribe this magnetoresistance to spin‐dependent electron scattering due to spin canting of the manganese oxide.

31p-S-4 Giant Magnetoresistance in Magnetic Manganese Oxide with Intrinsic Antiferromagnetic Spin Structure

The electronic structure of the perovskite LaCoO$_3$ for different spin states of Co ions was calculated in the LDA+U approach. The ground state was found to be a nonmagnetic insulator with Co ions in a low-spin state. Somewhat higher in energy we found two intermediate-spin states followed by a high-spin state at significantly higher energy. The calculation results show that Co 3$d$ states of $t_{2g}$ symmetry form narrow bands which could easily localize whilst $e_g$ orbitals, due to their strong hybridization with the oxygen 2$p$ states, form a broad $\sigma^*$ band. With the increase of temperature which is simulated by the corresponding increase of the lattice parameter, the transition from the low- to intermediate-spin states occurs. This intermediate-spin (occupation $t_{2g}^5e_g^1$) can develop an orbital ordering which can account for the nonmetallic nature of LaCoO$_3$ at 90 K$<$T$<$500 K. Possible explanations of the magnetic behavior and gradual insulating-metal transition are suggested.

https://arxiv.org/pdf/cond-mat/9709060.pdf

A. Cheikhrouhou

Papers

Effects of partial Mn-substitution on magnetic and magnetocaloric properties in Pr0.7Ca0.3Mn0.95X0.05O3 (Cr, Ni, Co and Fe) manganites

Impact of sintering temperature on the magnetic and magnetocaloric properties in Pr0.5Eu0.1Sr0.4MnO3 manganites

3D-Ising ferromagnetic characteristics and magnetocaloric study in Pr0.4Eu0.2Sr0.4MnO3 manganite

Influence of transition metal doping (Fe, Co, Ni and Cr) on magnetic and magnetocaloric properties of Pr0.7Ca0.3MnO3 manganites

Structural, magnetic and magnetocaloric properties in La0.5−xRexCa0.5MnO3 manganites (x = 0; 0.1 and Re = Gd, Eu and Dy)