Showing papers on "Colossal magnetoresistance published in 1969"
TL;DR: In this article, a simple type of exchange interaction between charge carriers in a broad energy band and localized magnetic moments was discussed for a ferromagnetic semiconductor, which causes a splitting of the energy band into two bands for the different spin directions, and spin disorder scattering of the charge carriers.
Abstract: The consequences of a simple type of exchange interaction between charge carriers in a broad energy band and localized magnetic moments will be discussed for a ferromagnetic semiconductor. The interaction causes (1) a splitting of the energy band into two bands for the different spin directions, (2) spin disorder scattering of the charge carriers. The calculated temperature and field dependence of the magnetoresistance are compared with experimental data of CdCr2Se4. The magnetoresistance of compounds MeCr2S4, Me=Fe, Co, Cd was measured. For n‐type CdCr2S4 and for p‐type FeCr2S4 and p‐type CoCr2S4, the magnetoresistance −Δρ/ρ0 was found to be 0.78, 0.05, and 0.05, respectively, at 12 kOe near Tc, whereas n‐type FeCr2S4 and CoCr2S4 show no effect. The magnetoresistance of the system Fe1−xCdxCr2S4 was also measured. The temperature dependence of the polar magneto‐optical Kerr effect of CdCr2Se4 is discussed in connection with the described model for the energy bands.
69 citations
TL;DR: The magnetoresistance of semiconducting KTaO 3 has been investigated Low field results indicate that the bottom of the conduction band consists of 3 or 6 ellipsoids along the crystalline axes, similar to the energy band model predicted by as discussed by the authors.
11 citations
TL;DR: In this paper, the magnetoresistance of strongly compensatedn-type GaAs doped with Cr and O has been measured at 77°K temperature and the electron concentrations of the samples were between 3.8×1017 and 1.6×1018 cm−3 at room temperature.
Abstract: The magnetoresistance of strongly compensatedn-type GaAs doped with Cr and O has been measured at 77°K temperature. The electron concentrations of the samples were between 3.8×1017 and 1.6×1018 cm−3 at room temperature. In low magnetic fields negative magnetoresistance was observed at liquid nitrogen temperature. The characteristics of this anomalous negative magnetoresistance were shown to be very similar to those observed at liquid He temperatures in heavily doped semiconductors. In weak fields the negative magnetoresistance was proportional to the square of the magnetic field, and showed saturation in the magnetic field range of 4000–6000 G. To account for the observed effects it was postulated that metal-like impurity band conduction is the dominant mechanism of the charge carrier transport in our samples. The observed features of the negative magnetoresistance are shown to be consistent with the model of scattering of electrons in the impurity band by localized magnetic moments. For the average value of the localized magnetic moments a value of the order of 2–3 Bohr magneton was deduced from the experimental data. It is shown that the strong compensation may play an important role in the formation of impurity band at 77°K temperature and above it.
8 citations
5 citations
TL;DR: In this paper, the low temperature magnetoresistance of a metal with paramagnetic impurities is studied in the case of large phase shift η for the potential scattering, and it is shown that when cos 2η < 0, the impurity magnetoreduction may become positive for sufficiently strong fields and low temperatures.
Abstract: The low temperature magnetoresistance of a metal with paramagnetic impurities is studied in the case of large-phase shift η for the potential scattering. It is shown that when cos 2η<0 the impurity magnetoresistance may become positive for sufficiently strong fields and low temperatures.
4 citations