of Sec. IVA indicates that acoustical mode scattering is still important. Optical mode scattering is nearly frozen out at this temperature so the energy independent mechanism used for comparison has been labeled HN corresponding to scattering by neutral impurities. 27 Such a mechanism is at least a possibility although considerations given in Sec. IVA argue against it.As the temperature is lowered from 19° to 6°K the mobility increases only slightly. However, as Fig. 9 S UPERCONDUCTIVITY and ferromagnetism have been studied in a number of metallic compound systems by Matthias, Suhl, and Corenzwit. 1 The present paper reports more detailed studies of solid solutions in the system CeRu2-GdRu2 and of some other materials. The purpose of the work 2 has been to find out if superconducting materials can become ferromagnetic and if ferromagnetic materials can be superconducting at the same time, and more generally to know the influence of the one property on the other.
EXPERIMENTAL METHODMeasurements have been made of magnetic moment as dependent on field strength H, and temperature T, over the range #=0 to 12 000 oe, T=1.3 to 300°K. Moments were usually measured by a null method using a pendulum magnetometer supporting the specimen in a field gradient, with strain gauge sensing elements, as previously described. 3 On some occasions the material was surrounded by a search coil, the field reversed (or 1 B. T. Matthias, H. Suhl, and E. Corenzwit, Phys. Rev. Letters 1, 449 (1958). 2 For a brief report of part of this work see J. Appl. Phys. 31, 235 (1960). 3 R. M. Bozorth, H. J. Williams, and D. E. Walsh, Phys. Rev. 103, 572 (1956); R. M. Bozorth and D. D. Davis, Phys. Rev. 118, 1543 (1960).indicates, the high field effect has become considerably more important. This appears to be due to the importance of impurity scattering at the lower temperature and is just the result expected from the amount of scattering chosen to fit the mobility data as discussed in Sec. IVC. The general shape of the theoretical curve in Fig. 9 is in good agreement with experiment for scattering by charged centers (£= §) but does not agree well in the case of acoustical scattering (p= -J).the the sample and coil rotated 180°) and a galvanometer deflection noted. Hysteresis loops were measured using the pendulum magnetometer in a carefully calibrated electromagnet, taking into account the nonlinearity and hysteresis of the magnet and in some cases the field produced at the specimen by the current through the balancing coil, which annuls the moment of the specimen. The initial magnetization curves were measured after cooling from a sufficiently high temperature in zero field.The materials were prepared by melting in the argon arc. X-ray examination showed them to be true solid solutions with, in some cases, a trace of uncombined ruthenium.The specimens, having usually a dimensional ratio of about 4, were mounted at the center of the balancing coil. The sensitivity of the pendulum magnetometer was about 0.004 cgs unit in high fields, the largest mom...
