Pouvoir rotatoire paramagnétique et aimantation de l'ion cérium dans l'éthylsulfate hydrate

The theory of the magnetic properties of rare earth salts: cerium ethyl sulphate

“…The measurements of rotation by Becquerel et al (1938) between 1 and 4°K show discrepancies from the theory in which two low-lying doublets are concerned. This has been attributed by Finkelstein (1939) to an interaction between the ions and will not be considered here, except that we should like to point out th at when measurements are made in large magnetic fields, levels which come from different doublets may be brought close together.…”

“…are sufficiently like those of Bogle et al (1951) to give agreement with their measurements at low temperatures. The agreement at higher temperatures with Fereday & Wiersma's anisotropy (1935) and with the Verdet constant of Becquerel et al (1938) is adequate except for the discrepancy near 14° K. I t does not seem profitable to consider any modification of the numerical work until direct measurements of Xu and are available over a wider range of temperatures. I t will also be noticed th at X and V a will only be proportional if the states of the ion are eigenstates of the total angular momentum.…”

“…These were then combined to give values for and x± a t 14* 18 and 20*45° K. Extrapolating the measurements of Bogle et al to these temperatures good agreement is obtained with the values of Fereday & Wiersma. Becquerel et al (1938) investigated the Faraday effect by measuring th pendence of the rotation of the plane of polarization of fight passing through the crystal, on temperature and magnetic field, from 1 to 300° K. Because of double refraction this could only be done with the light directed along the hexagonal axis. They then assumed th at the rotation was proportional to the parallel susceptibility, and using Fereday & Wiersma's values at 14*18 and 20*45° K determined their constant of proportionality.…”

“…Unfortunately, different workers have used different substances, so th a t there are very few salts for which both the absorption spectra and the susceptibilities of a single crystal are known. The work of Becquerel, de Haas & Van den Handel (1938) on the ethyl sulphates has been an outstanding attem pt to obtain full magnetic information about a sequence of isomorphous salts.…”

Microwave Modulation of Light in Paramagnetic Crystals

“…(25) and (26) yield about the same value for <$>M under the same conditions. 34,35 In either case a microwave field of one oersted fulfills the condition (4). The spin-lattice relaxation time in the Nd salt has recently been measured by observation of the recovery of dc Faraday rotation after saturation.…”