Environmental influence on the observed relaxation behaviour of two chromium systems

EPR recovery curves were measured for KCr alum and ruby with 2.7% chromium. A considerable influence of the heat transport properties of the bath is observed. Taking care of this influence a spin relaxation time τ = (0.7 ± 0.2) ms could be observed for ruby and a spin-lattice relaxation time T1 ∝ T-1. For KCr alum an anomalous behaviour of T1 was observed which may be due to a phonon bottleneck

Le conte de fées français dans les planches populaires néerlandaises : trois versions du « Petit Chaperon rouge » (1781-1911)

Dans la seconde moitié du xviiie siècle, on voit paraître, aux Pays-Bas, les premières planches populaires figurant des contes de fées. Le présent article analyse trois planches populaires néerlandaises publiées entre 1780 et 1911 représentant « Le Petit Chaperon rouge ». Si elles se ressemblent beaucoup à première vue, elles présentent néanmoins des différences notables (nombre, disposition, composition des images, sens de lecture, technique d’illustration, choix des scènes). Les éditeurs créent ainsi différentes versions du même conte. Le texte étant réduit à une simple légende, les illustrations jouent un rôle central dans ce processus : elles introduisent des variantes et parfois intensifient le suspense. En outre, les différentes versions du « Petit Chaperon rouge » semblent refléter plusieurs opinions ayant cours dans les débats pédagogiques des xviiie et xixe siècles, et elles renseignent sur l’évolution du livre pour enfants pendant cette période.In the second half of the eighteenth century, the first popular boards figuring fairy tales appear in Netherland. Three boards published between 1780 and 1911, representing the tale “Little Red Riding Hood”, are analyzed in this article. Although they look very much alike, they reveal important differences in the number, disposition, composition of pictures, sense of reading, techniques of illustration, choice of scenes. Editors create different versions of the same tale. The text being reduced to the status of mere captions, the illustrations play the central function in the narrative, introducing variations and sometimes intensifying the suspense. Moreover, the different versions of “Little Red Riding Hood” seem to reflect several opinions expressed in pedagogical debates during the eighteenth and nineteenth centuries, and they provide information about the evolution of children’s books during this period

Structural and magnetic properties of the Bi-MnBi controlled eutectic

The structure and magnetic properties of the unidirectionally solidified Bi-MnBi eutectic are studied over a range of growth rates from 0.83 to 630 cm/h. Considerable changes in the microstructure of the eutectic occur in this range

Anomalous magneto-structural behavior of MnBi explained: a path towards an improved permanent magnet

Low-temperature MnBi (hexagonal NiAs phase) exhibits anomalies in the lattice constants (a, c) and bulk elastic modulus (B) below 100 K, spin reorientation and magnetic susceptibility maximum near 90 K, and, importantly for high-temperature magnetic applications, an increasing coercivity (unique to MnBi) above 180 K. We calculate the total energy and magneto-anisotropy energy (MAE) versus (a, c) using DFT+U methods. We reproduce and explain all the above anomalies. We predict that coercivity and MAE increase due to increasing a, suggesting means to improve MnBi permanent magnets.Comment: 4 pages, 5 figure

Spin-lattice relaxation in potassium chromium alum

A comparison is made between the results of low-frequency relaxation measurements on potassium chromium alum placed in liquid helium and in vacuum, respectively. It is found that only a part of the lattice oscillations is involved in the spin-lattice relaxation process. The spin-lattice relaxation time was found after correcting the time constants of the vacuum measurements by experimental shortening factors. The differences between the spin-lattice relaxation time and the time constants from the liquid-helium measurements can be explained for the greater part by the finite thermal conductivity of the liquid helium

Thermal conductivity of tin-doped bismuth between 50 mK and 7K

The authors report on the thermal conductivity of tin-doped bismuth between 50 mK and 27K. A quantitative interpretation of the data is presented. At the lowest temperatures the electronic thermal conductivity dominates, but above 0.1K lattice waves carry most of the heat. Below 1K phonons are scattered mostly by crystal boundaries, while near the dielectric maximum point defects are important. Their scattering rate is directly proportional to the atomic concentration of the tin impurity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48999/2/jcv18i15p3001.pd

Anomalan magnetootpor monokristala dopiranog bizmuta

Measurements of magnetoresistance of single crystals of bismuth doped with tin and lead in the temperature range 100 K to 300 K are reported. Both tin and lead have a marked effect in changing the band structure of bismuth. Temperature variations show that with the increased concentration of impurity, Dr/r0 is less dependent on temperature, and the magnetic field variation of Dr/r0 does not obey the quadratic dependence on magnetic field strength.Izvješćujemo o mjerenjima magnetootpora monokristala bizmuta dopiranog kositrom i olovom pri temperaturama 100 do 300 K. I kositar i olovo jako utječu na strukturu vrpci u bizmutu. Mjerenja pokazuju da za povećane koncentracije onečišćenja, ∆ρ/ρ0 slabije ovisi o temperaturi, a promjene ∆ρ/ρ0 s magnetskim poljem nemaju kvadratnu ovisnost o jakosti magnetskog polja