S 162 SHORT COMMUNICATIONS

89. M e a s u r e m e n t s on the m a g n e t i c suscept ibiHties of AgMn and CuMn alloys. A. VAN ITTERBEEK, W. POLLUNTIER and G. PEELAERTS.

Ins t i tuut voor Lage Temperaturen en Technische Physica, Louvain, Belgium.

Measurements have been carried out on alloys of AgMn and CuMn with different concentrations of manganese between room temperature and liquid hydrogen temper- atures. A paramagnetic behaviour has been found. We examined especially the depen- dence of the susceptibilities on the field strength; no field dependence could be detected except in some of the AgMn alloys, bu t this effect originated from small ferromagnetic impurities, which were determined by means of the method of H o n d a.

The concentration of the manganese has been determined magnetically and com- pared with determinations based on the electrical resistance.

90. Magnet ic Suscept ibi l i ty of Electrons and Donors in N - t y p e Sil icon. E. SONDER and D. K. STEVENS.

Sohd State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A.

The magnetic susceptibility • of silicon has been measured as a function of tempera- ture (3°K to 300°K) for a range of donor concentrations (3 × l0 is to 3 × 1019 cm-8). The donor concentrations were obtained from Hall coefficient measurements on companion specimens. The contribution to Z from conduction electrons and neutral donors was determined by subtracting the susceptibility of high-purity silicon. The difference, AS, shows two ranges of behavior: At high temperature zJ X is dominated by the orbital diamagnetism of conduction electrons and its value indicates a squared- reciprocal-mass ratio of 8 as compared to 12 expected from cyclotron resonance. At low temperatures A S is governed by occupied donors; higher puri ty specimens show a simple Curie law dependence whose slope is proportional to the donor concentration. At the higher donor concentrations interaction between donor atoms (impurity banding) eauses a deviation from Curie's law.

91. Magnet ic re laxat ion phenomena in g e r m a n i u m at l ow t empera tures . L. VAN GERVEN, A. VAN ITTERBEEK and L. DE LAET.

Ins t i tuut voor lage Temperaturen en technische Fysica, Leuven (Belgie).

By means of an experimental arrangement and the usual methods for magnetic resonance absorption studies, some magnetic relaxation phenomena have been found in pure and doped germanium at low temperatures, using relatively low radiofrequen- cies (20 ~ 100 MHz). Two different absorption lines have been observed. They differ by their sign and by the temperature region, where they occur. Their properties and possible origins are discussed, using an extension of the so called "modified" B 1 o c h theory of the magnetic resonance phenomenon.

92. Paramagne t i c Relaxat ion in Single Crystals at Liquid H e l i u m T e m p e r a - tures . T. HASEDA.

The Research Inst i tute for Iron, Steel and Other l~etals. T6hoku University, Sendai, Japan.

Paramagnetic relaxations in single crystal samples are measured. In CoNH4-Tutton salt, the anomalous tendency of dpsL/dHc, is found also in single crystals. Anisotropy is not observed in the tendency of dpsL/dHc neither in the cobaltous salt nor in the