Showing papers on "Colossal magnetoresistance published in 1982"

Chapter 9 Transport properties of ferromagnets

Abstract: Publisher Summary This chapter discusses the transport properties of ferromagnets. The focus is on transport properties of the transition ferromagnets Fe, Co, and Ni and their alloys. In pure ferromagnetic metals, the “internal magnetoresistance” enhances the resistivity that is no longer proportional to the concentration of impurities. This effect is particularly important for Fe and a high transverse magnetoresistance. For demagnetized Fe polycrystals, it was pointed out that the apparent residual resistivity ratio would never increase beyond about 300, however pure the sample. It is now standard practice to measure the low temperature resistivity of Fe samples in a saturating longitudinal magnetic field to eliminate transverse magnetoresistance. This can reduce the apparent resistivity by a factor of five or more. In principle, a correction should still be made for the longitudinal magnetoresistance. In Ni samples, the enhancement of the residual resistivity by the internal magnetoresistance is less important than in Fe but still significant. For non-magnetic alloys, the low temperature magnetoresistance behavior generally follows Kohler's rule. Schwerer and Silcox showed by a careful study of dilute Ni alloy samples that for a given series of alloys the ordinary magnetoresistance follows a Kohler's rule, but that the Kohler function varied considerably with the type of scatterer.

Magnetization and Magnetoresistance of MnSi. I

Abstract: Magnetization and magnetoresistance of itinerant electron helical magnet MnSi has been studied down to 0.45 K. A large negative magnetoresistance is observed especially around Neel temperature T N in accord with the theoretical expectation. Below 1 K, however, a positive magnetoresistance is found and it is attributed to the normal magnetoresistance due to impurity scattering. Anomalous peaks in the magnetization and magnetoresistance are observed just below T N between about 1.0 and 2.2 kOe and the existence of two new phases are suggested.

Positive Magnetoresistance of Thin Gold Films at Low Temperatures

Abstract: The electrical resistance of ultra thin gold films increases as the temperature is lowered below 6 K. The magnetoresistance is positive and anisotropic. A logarithmic dependence of the resistance on magnetic field has been observed. The results are inqualitative agreement with the recent theories of the electron localization in two-dimensional systems.

Low-field magnetoresistance in AuCuMn alloys

Abstract: The magnetoresistance of (Au1-xCux) Mn spin glass alloys has been studied for large variations of copper and manganese atom concentrations at temperatures above the freezing temperature. The magnetoresistance has been observed to depend strongly on the concentration of both the magnetic (Mn) and non-magnetic (Cu) impurities. The variation in the Cu concentration for a constant value of the Mn concentration has enabled the authors to study the dependence of magnetoresistance on the strength of the RKKY interaction.

Weak-field magnetoresistance coefficients and the related magnetoresistance skewness effect

Abstract: 2014 This work presents an overall view of the measurements concerning the galvanomagnetic coefficients in the weak-field case with an attempt to emphasize the physical significance of the results. The method is based on the anisotropy induced in the electrical behaviour by the magnetic field. Emphasis is also given in explaining the magnetoresistance skewness effect. A comparison with the classical method is also presented to indicate the advantage of the method. Finally the method is analyzed for measurements on n-type Ge for which the energy band model is derived to obtain the ml/mt ratio which in return is used to obtain the scattering factor, the carrier density and the drift mobility. The results are in accordance with previous findings. Revue Phys. Appl. 17 (1982) 49-54 FÉVRIER 1982, PAGE