[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Journal of Physics Condensed Matter: Preface

https://iopscience.iop.org/article/10.1088/1468-6996/16/2/023501/pdf

Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications.

Magnetocaloric effect: From materials research to refrigeration devices

A2B′B″O6 perovskites: A review

The field-induced evolution of the magnetic ordering in (CuBr)Sr${}_{2}$Nb${}_{3}$O${}_{10}$ with a $⅓$ magnetization plateau has been investigated by neutron diffraction under magnetic fields up to 10 T. With an increasing magnetic field, the zero-field helical antiferromagnetic (AFM) phase, AF1, with \ensuremath{\kappa} $=$ [0 $⅜$ $\textonehalf{}$] is replaced by a simple ferromagnetic phase with \ensuremath{\kappa} $=$ [0 0 0], the formation of which is, however, retarded by the appearance of a second AFM, AF2, with \ensuremath{\kappa} $=$ [0 $⅓\ensuremath{\sim}0.46$]. Upon further increasing of the magnetic field, the AF2 phase disappears and only the ferromagnetic phase persists. The results clearly show that the magnetization plateau, induced by the competition between field-induced ferromagnetic, F, and AF2 phases, is coincidentally situated at $M$ $=$ $⅓$ ${M}_{S}$ of the dc magnetization curve. The AF1 and AF2 phases have strongly differing magnetic propagation vectors and are therefore not directly related.

/pdf/field-induced-evolution-of-magnetic-ordering-in-the-quantum-xbtzjkmi37.pdf

Field-induced evolution of magnetic ordering in the quantum spin system (CuBr)Sr 2 Nb 3 O 10 with a ⅓ magnetization plateau

By employing temperature (T)-dependent soft x-ray magnetic circular dichroism (XMCD) in the Fe and Cr 2p absorption edges, the electronic structures of Li 0.5 FeCr 1.5O4 spinel ferrite, which exhibits magnetization compensation, have been investigated. This work provides evidence that (i) both Fe and Cr ions are trivalent, (ii) most of Fe 3 + ions occupy the A (Td) sites, while Cr 3 + ions occupy the B (Oh) sites, (iii) the magnetic moments of Fe and Cr ions are coupled antiferromagnetically, and (iv) they are reversed at ∼ 255 K. The sum-rule analysis of Fe and Cr 2p XMCD spectra reveals that the orbital magnetic moments of Fe and Cr ions in Li 0.5 FeCr 1.5O4 are much larger than those of metallic Fe and Cr, implying the large spin–orbit coupling and the non-fully occupied t 2 g orbitals of Fe 3 + and Cr 3 + ions. Based on these findings, we have provided a comprehensive model for the electronic and spin configurations of Fe and Cr ions in (Fe)A[ Li 0.5 Cr 1.5]BO4.

Electronic structures and magnetization reversal in Li 0.5 FeCr 1.5 O 4

The effect of electron doping on the magnetic properties of the brownmillerite type bilayered compounds has been investigated by neutron powder diffraction in La substituted Ca2.5−xLaxSr0.5GaMn2O8 compounds (x = 0.05 and 0.1), in comparison with the undoped compound (x = 0). In all compounds, a long-range three-dimensional collinear antiferromagnetic (AFM) structure is found below the Neel temperature TN of the respective compound, whereas, well above TN, three-dimensional short-range magnetic ordering is observed. In the intermediate temperature range just above TN, a strong effect of electron doping (La substitution) on the magnetic correlations has been observed. Here, a short-range AFM correlation with a possible dimensionality of three has been found for substituted compounds (x = 0.05 and 0.1) as compared to the reported two-dimensional long-range AFM ordering in the parent compound. With increasing electron doping, a decrease in TN is also observed. The short-range magnetic correlations set in over a large temperature range above TN. A magnetic phase diagram in the x–T plane is proposed from these results.

Effect of electron doping on the magnetic correlations in the bilayered brownmillerite compound Ca2.5−xLaxSr0.5GaMn2O8: a neutron diffraction study

Nanocrystalline HoCrO4 powder was synthesized by a combustion technique using glycine and citric acid as the fuels in different oxidant-to-fuel ratios. Fuel-deficient glycine-nitrate combustion reaction resulted in zircon type HoCrO4 free from HoCrO3 phase. The crystallite size for the phase pure product after calcination at 575 °C in oxygen atmosphere was found to be 34 nm by X-ray line broadening. The TEM observations showed highly porous structure. Magnetic measurements reveal the ferromagnetic nature of HoCrO4 nano particles with 7 = 18 K. The compound shows high remanence of 30.4 emu . g1 and low coercivity of -0.0343 T.

S. M. Yusuf

Papers

Field-induced evolution of magnetic ordering in the quantum spin system (CuBr)Sr 2 Nb 3 O 10 with a ⅓ magnetization plateau

Electronic structures and magnetization reversal in Li 0.5 FeCr 1.5 O 4

Effect of electron doping on the magnetic correlations in the bilayered brownmillerite compound Ca2.5−xLaxSr0.5GaMn2O8: a neutron diffraction study

Nanocrystalline HoCrO4: facile synthesis and magnetic properties

Short-range and long-range incommensurate magnetic ordering in the frustrated antiferromagnets Ca 3 Co 2-x Fe x O 6 : A neutron diffraction study