[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 electronic structure of Heusler alloys having mixed magnetic phases, comprising of vicinal anti-ferromagnetic and ferromagnetic orders, is of great significance. We present the results of an electronic structure study on NixCu1−xMnSb Heusler alloys, using Mn-2p core-level photoemission spectroscopy. Room temperature data in the paramagnetic phase reveal a non-monotonic variation of both electron correlation strength and conduction-band hybridization such that the former enhances while the latter weakens for compositions showing a mixed phase relative to compositions at the phase boundaries to the ordered phases. The results suggest a possible electronic driving force for settling mixed-magnetic phases.

Nature of electron correlation and hybridization in NixCu1−xMnSb Heusler alloys

We have investigated the magnetocaloric properties of Ni2+xMn1−xSn (x = 0, 0.05 and 0.1) Heusler alloys by using the dc-magnetization measurement technique. A reduction in the paramagnetic to ferromagnetic transition temperature (Curie temperature, TC) has been observed with a substitution of Ni at the Mn site (from TC ∼ 349 K for x = 0 to ∼ 317 K for x = 0.1 sample). With an increase in x, a very small reduction in the value of the magnetic entropy change −ΔSM has been observed. The −ΔSM values have been found to be ∼ 2.1, 1.8 and 1.5 J kg−1 K−1 for x = 0, 0.05 and 0.1 samples, respectively, for a magnetic field change from 0 to 30 kOe. The hysteresis loss has also been found to be very small for all the compositions. Moreover, a non-toxic as well as a cost effective nature of the studied Ni2+xMn1−xSn alloys can make them promising candidates for magnetic refrigeration near room temperature.

Magnetocaloric properties of Ni2+xMn1−xSn Heusler alloys

Experimental detection of spin dynamics of the quantum spin liquid phase, which occurs when the quantum fluctuations lead to fractionalized spin states, remains a challenge. In this paper, we illustrate spin-liquid signatures in the geometrically frustrated layered kagome system $\mathrm{YBa}{\mathrm{Co}}_{4\ensuremath{-}x}{\mathrm{Fe}}_{x}{\mathrm{O}}_{7+\ensuremath{\delta}}$ ($x=0$ and $x=0.6$) over a wide temperature range using micro-Raman spectroscopy. The thermal response of the gapped broad band over a high temperature range possibly marks a spin liquid phase in this system. We report the appearance of sharp spectral features in the high temperature regime with unusual thermal behavior for $\mathrm{YBa}{\mathrm{Co}}_{4\ensuremath{-}x}{\mathrm{Fe}}_{x}{\mathrm{O}}_{7+\ensuremath{\delta}}$ ($x=0.6$). Besides, atypical oscillation of a phonon mode frequency with temperature suggests an unconventional electron-lattice coupling in the doped compound via a strong correlation between their lattice vibration and magnetic spin dynamics.

Spin-liquid signatures in geometrically frustrated layered kagome compounds YBa Co 4 − x Fe x O 7 + δ

The emergence of low temperature glassy phase in widely known itinerant ferromagnet SrRuO3 is remotely understood. In order to understand this aspect, we have undertaken a detailed temperature dependent (5–250 K) neutron diffraction study. We observe a freezing of the octahedral tilt near the ferromagnetic transition and an unusual deviation in the octahedral tilt near the onset of low temperature spin glass like phase. A reduction of the ordered magnetic moment and a decline in the total integrated magnetic intensity is observed around the temperature where the glassy behaviour starts to appear. The magnetotransport study also reveals the possibility for an additional magnetic ordering by demonstrating a peak in magnetoresistance at the low temperature side as well. The neutron diffraction study presented here provides useful information to understand the observed unusual low temperature magnetic phenomena in SrRuO3.

Freezing of the octahedral tilt near ferromagnetic transition and appearance of a glassy phase at low temperature driven by the tilt instabilities in SrRuO3

Study on magnetism in two-dimensional (2D) spin–lattices is advancing rapidly. In this work, phase-pure botallackite (Bo) (Cu2(OH)3Br), a quasi-2D S = 1/2 anisotropic triangular spin–lattice is sta...

S. M. Yusuf

Papers

Nature of electron correlation and hybridization in NixCu1−xMnSb Heusler alloys

Magnetocaloric properties of Ni2+xMn1−xSn Heusler alloys

Spin-liquid signatures in geometrically frustrated layered kagome compounds YBa Co 4 − x Fe x O 7 + δ

Freezing of the octahedral tilt near ferromagnetic transition and appearance of a glassy phase at low temperature driven by the tilt instabilities in SrRuO3

Exploring Magnetic XY Behavior in a Quasi-2D Anisotropic Triangular Lattice of Cu(II) by Functionalized Graphene