Showing papers on "Magnetoresistance published in 1986"
TL;DR: Quantization of the Hall effect and concomitantly vanishing magnetoresistance are observed in a GaAs/(AlGa)As superlattice structure whose electronic spectrum exhibits dispersion in all three spatial dimensions.
Abstract: Quantization of the Hall effect and concomitantly vanishing magnetoresistance are observed in a GaAs/(AlGa)As superlattice structure whose electronic spectrum exhibits dispersion in all three spatial dimensions.
201 citations
TL;DR: In this paper, the electrical resistivity, magnetoresistance and magnetic susceptibility of single crystalline Ce x La 1-x Cu 6 ( x = 0-1) have been measured down to mK region.
Abstract: The electrical resistivity, magnetoresistance and magnetic susceptibility of single crystalline Ce x La 1- x Cu 6 ( x =0-1) have been measured down to mK region. As the Ce concentration is increased, the consecutive change from the dilute (incoherent) Kondo regime to the Kondo lattice (coherent) regime is observed. The characteristic features in the coherent Kondo regime are clearly observed in the resistivity and the magnetoresistance above x =0.7. The low temperature resistivity in Ce x La 1- x Cu 6 shows a T 2 dependence and the residual resistivity follows the Nordheim law. As for the coherence effect in CeCu 6 , the resistivity follows a T 2 dependence below 0.1 K, the magnetoresistance changes from negative to positive below about 0.15 K within applied magnetic fields and the susceptibility shows an enhanced Pauli paramagnetism below 1 K.
143 citations
TL;DR: In this article, a model involving quasi-elastic inter-Landau-level scattering is proposed to explain the three main features of recent experiments by Bliek and co-workers on the dissipative transverse magnetoresistance of the two-dimensional electron gas in GaAs/(AlGa)As heterostructures in which there is a narrow constriction in the conducting channel.
Abstract: A model involving quasi-elastic inter-Landau-level scattering is proposed to explain the three main features of recent experiments by Bliek and co-workers on the dissipative transverse magnetoresistance of the two-dimensional electron gas in GaAs/(AlGa)As heterostructures in which there is a narrow constriction in the conducting channel. These features are the high breakdown current densities observed, the magnetic field values of the 'quantum' steps in the magnetoresistance and the quantised values of the magnetoresistance.
121 citations
TL;DR: In this article, a review of the properties and applications of the permalloy magnetoresistive sensors of magnetic fields is presented, along with the manufacturing and biasing methods.
Abstract: Presents a review of the properties and applications of the permalloy magnetoresistive sensors of magnetic fields. Information on the manufacturing and biasing methods is given. The basic parameters-sensitivity, dimensions, linearity, resolution and transducer errors-and methods for improving them are analysed. The examples of permalloy microsensors, miniature sensors and large-area sensors are presented. The application of permalloy magnetoresistors to measuring magnetic fields and constructing electrical and non-electrical transducers is described.
74 citations
TL;DR: In this article, the temperature-dependent magnetoresistance of the heavy-electron Ce compounds is calculated with the use of the periodic Anderson model, and the obtained results are qualitatively in good agreement with the experimental evidences of CeAl 3 and CeCu 6.
Abstract: The temperature-dependent magnetoresistance of the heavy-electron Ce compounds is calculated with the use of the periodic Anderson model. It is pointed out that the magnetoresistance has a minimum-structure and may change its sign from negative to positive as the temperature is decreased. The obtained results are qualitatively in good agreement with the experimental evidences of CeAl 3 and CeCu 6 .
60 citations
TL;DR: Thin Nb films from 30 to 150 A-circle thick have been electron-beam evaporated onto sapphire substrates with aluminum overlayers, then deposited to protect the surface.
Abstract: Thin Nb films from 30 to 150 A-circle thick have been electron-beam evaporated onto sapphire substrates with aluminum overlayers, then deposited to protect the surface. T-italic/sub c-italic/'s and magnetoresistance were found to be consistent with localization models and measured parallel critical fields fit a generalized Ginzburg-Landau theory. Perpendicular critical fields, however, were found to have an anomalous curvature near T-italic/sub c-italic/. These results, we believe, are due to the disorder of the film and have also been seen in other systems.
44 citations
TL;DR: In this paper, the temperature and magnetic field dependence of the electrical conductivity in a number of metallic glasses has been investigated and an analysis of these results is presented in terms of the models for weak localisation and e-e interaction effects in disordered metals.
Abstract: Results are presented for the temperature and magnetic field dependence of the electrical conductivity in a number of metallic glasses. The temperature dependence has been measured over the range 100 mK to 300K, while the magnetoresistance has been measured at temperatures below 1K and in fields up to 10 T. An analysis of these results is presented in terms of the models for weak localisation and e-e interaction effects in disordered metals.
43 citations
TL;DR: In this article, low temperature specific heat and magnetoresistance measurements have been performed on the ferromagnetic semiconducting compound UFe4P12 in the vicinity of its Curie temperature Tc=3.15 K.
39 citations
TL;DR: In this article, a new model is proposed to explain important experimental results on the Quantum Hall effect without explicit reference to localized electron states, where the main assumption is a moderate inhomogeneity in the electron density across the width of the sample.
Abstract: A new model is proposed to explain important experimental results on the Quantum Hall effect. The existence of plateaus in the Hall resistance and broad minima in the magnetoresistance can be explained without explicit reference to localized electron states. The main assumption is a moderate inhomogeneity in the electron density across the width of the sample. Earlier experiments on the distribution of the Hall voltage across the sample can be explained when a gradient in the electron density is assumed.
38 citations
TL;DR: In this article, the relation between magnetic field and resistance variations is described first and conditions are given to achieve reliable operation even though the magnetic layers show more imperfections, while linearization of the square characteristic and the design of several sensor types are discussed.
37 citations
TL;DR: In this article, the magnetoresistance of a series of metallic glasses, including Mg80Cu20, Cu50Lu50, Pd80Si20, Y 80Si20 and Cu57Zr43, was measured at low temperature.
Abstract: The authors present magnetoresistance measurements at low temperature on a series of metallic glasses: Mg80Cu20, Cu50Lu50, Pd80Si20, Cu50Y50, Y80Si20, Cu57Zr43, CuYGd and CuLuGd. The magnetoresistance clearly exhibits three-dimensional localisation effects with a strong influence of the spin-orbit scattering: the magnetoresistance is negative for weak spin-orbit scattering (Mg80Cu20) and positive for strong spin-orbit scattering (Cu50Lu50, Pd80Si20), and changes from positive at low field to negative at high field for intermediate spin-orbit scattering (Cu50Y50, Cu57Zr43). The magnetoresistance curves can be accounted for by only localisation terms for most alloys and interaction effects are significant only for Y80Si20. An additional contribution from superconducting fluctuations is observed for the superconducting alloy Cu57Zr43. The analysis of the magnetoresistance yields the spin-orbit and inelastic scattering rates. The inelastic scattering rate of the alloys varies as T2 at high enough temperature and departs from T2 below about 5K. The measurements in a dilution refrigerator on Cu50Y50 and Y80Si20 have shown a variation as T1/2 below 1K. They discuss the possible origin of such a variation. They finally present measurements on Cu50Y50 and Y80Si20 doped with Gd. Surprisingly the addition of magnetic Gd impurities does not depress strongly the localisation effects, as would be expected from the existing theories.
Patent•
10 Feb 1986TL;DR: A magnetic sensor for sensing magnetic fields including two flat layers of electrically conductive ferromagnetic material (11, 16) each having an in-plane easy axis of magnetization (EA1, EA2) and each producing a resistance variation under the influence of a magnetic field which originates from a source at an edge of the layer, which layers are situated a small distance apart parallel with respect to each other.
Abstract: A magnetic sensor for sensing magnetic fields including two flat layers of electrically conductive ferromagnetic material (11, 16) each having an in-plane easy axis of magnetization (EA1, EA2) and each producing a resistance variation under the influence of a magnetic field Ha which originates from a source at an edge of the layer, which layers are situated a small distance apart parallel with respect to each other. In order to increase the sensor's sensitivity to small magnetic fields, in operation the layers (11, 16) convey currents flowing in the same direction and are connected in parallel to the input terminals of a detection circuit (2, 9).
TL;DR: The transverse magnetoresistance of TMTSF 2 ClO 4 has been investigated in magnetic fields as high as 32 T, at low temperature down to 2.4 K.
TL;DR: In this article, the transverse magnetoresistance of TMTSF 2 ClO 4 was measured in pulsed high magnetic fields up to 35 T at T = 1.8−-4.2K for studying the field-induced spin density wave (FISDW) phase.
TL;DR: In this paper, the authors reviewed the progress of experimental studies on weak localization in two-dimensional (2D) systems in semiconductor inversion layers by means of magnetoresistance measurements.
TL;DR: In this article, the ground state and thermodynamic properties of the Coqblin-Schrieffer model in a crystalline field are investigated by means of the Bethe-ansatz method.
TL;DR: In this paper, the authors used the geometrical magnetoresistance method to measure the electron velocities and mobilities as functions of electric field in AlGaAs-GaAs modulation-doped structures at 77 K and found that high low-field mobility is not an important parameter for MODFET design and does not even significantly reduce the parasitic source resistance in an operating FET.
Abstract: We have used the geometrical magnetoresistance method to measure the electron velocities and mobilities as functions of electric field in AlGaAs-GaAs modulation-doped structures at 77 K. These structures had a variety of AlGaAs mole fractions and undoped setback layers resulting in different low-field mobilities in the different structures. We find that higher low-field mobility does not lead to a higher high-field velocity, and in fact, that at electric fields found in operating MODFET's, the mobilities and velocities were about the same in various AIGaAs-GaAs MODFET's. The results indicate that high low-field mobility is not an important parameter for MODFET design and does not even significantly reduce the parasitic source resistance in an operating FET. Furthermore, because of the strong electric field dependence of the mobility, low-field source resistance measurements are not adequate for determining the source resistance in an operating FET.
TL;DR: In this paper, the authors reported resistivity and magnetoresistance measurements of extremely pure monocrystalline MoSi2 (RRR approximately=1800), which behaves like a compensated metal with a very large magnetoresistivity at 4.2K which varies like H2 up to 7 T.
Abstract: The authors report resistivity and magnetoresistance measurements (4.2
TL;DR: In this article, experimental studies of the saturation magnetization 4πM s and galvanomagnetic properties of Co-M (M: early transition metal) have been systematically carried out at room temperature.
Abstract: Experimental studies of the saturation magnetization 4πM s , the saturation magnetostriction λ s and galvanomagnetic properties of Co-M (M: early transition metal) have been systematically carried out at room temperature. The composition dependence of 4πM s , of the anisotropic magnetoresistance Δ ρ/ρ 0 and of λ s are seen to depend on the valence difference between Co and M. The dependence of 4πM s on the composition reflects Friedel's theory. λ s and Δ ρ/ρ 0 depend on the number of electrons in the outer shell which varies with M. The quantum mechanical side jump mechanism is found to dominate the extraordinary Hall effect R s .
TL;DR: In this article, the induced uniaxial anisotropy constant, Ku, and the saturation magnetization, Ms, were examined as a function of thickness by a method involving the magnetoresisttance effect.
TL;DR: In this paper, high-resolution temperature-dependent electrical resistivity data on low-stage acceptor graphite fiber intercalation compounds are presented, showing that the magnitude of the effect and the temperature of the resistivity minimum are directly related to that of the residual resistivity of the compound.
TL;DR: In this article, the authors investigated the Hall voltage of UBe13 and the second superconducting critical magnetic field in the presence of heavy and light superconductors, and the effects of alloying with other compounds of U and Be.
Abstract: The Hall voltageU
xy
(H), magnetoresistance ρ(H), magnetization in the superconducting stateM(H), and the second superconducting critical magnetic field of UBe13 have been investigated. It is found thatU
xy
(H) is not linear, but has a maximum nearH=70 kOe atT=1.9 K. When the temperature rises from 1.9 to 100 K, the Hall coefficientR(H→0) decreases about 20 times from 2.5×10−10 to 1.35×10−11 Ω-cm/Oe. The rise of the magnetic field causes a strong decrease of the electrical resistance: atT=1.7 K, ρ(0)/ρ(210kOe)⋍5.8. From theH
c2 investigation for single crystals it can be seen that near Tc the anisotropy ofH
c2
is absent (it becomes visible only upon loweringT to 0.9T
c
). TheM
$$(H)_{T< T_c } $$
is similar to the typical dependence for type II superconductors. The thermodynamic critical fieldH
c
(0)≈1 kG, the Ginzburg-Landau parameter x ≈ 60, and the penetration depth λ≈4.10−5 cm. The effects of alloying a small quantity of iron and of neutron irradiation are investigated. The effects of alloying with other compounds of U and Be are also discussed. It is possible to suppose that UBe13 has two groups of carriers, “heavy” and “light,” with the anomalous properties of UBe13 caused by the specificity of the interaction between these two groups of carriers.
Patent•
19 Mar 1986TL;DR: In this paper, a yoke type magnetic transducer head utilizing a magnetoresistance effect was presented. But the magnetic yoke was not used in this paper. But it was used in the case of magnetic transducers, where a magnetoreduction effect sensing portion was provided so as to magnetically couple a cut-away portion in a magnetic circuit including an operation gap and a magnetic Yoke having in its one portion the cutaway portion.
Abstract: A yoke type magnetic transducer head utilizing a magnetoresistance effect in which a magnetoresistance effect sensing portion is provided so as to magnetically couple a cut-away portion in a magnetic circuit including an operation gap and a magnetic yoke having in its one portion the cut-away portion and in which a first bias magnetic field is applied to the magnetoresistance effect sensing portion by a first magnetic flux that is generated when a current is flowed through the magnetoresistance effect sensing portion, or when a current is flowed through both the magnetoresistance effect sensing portion and a bias conductor, which includes a hard magnetic layer for generating a second magnetic flux by which a second bias magnetic field is applied to the magnetoresistance effect sensing portion and for passing through the magnetic yoke a magnetic flux which cancels at least a part of the first magnetic flux which passes through the magnetic yoke.
TL;DR: Magnetoresistance measurements for accumulation layers at anodic oxide films on n-type Cd02Hg08Te in both perpendicular and tilted magnetic fields were presented in this paper.
Abstract: Magnetoresistance measurements are presented for accumulation layers at anodic oxide films on n-type Cd02Hg08Te in both perpendicular and tilted magnetic fields Five electric sub-bands are occupied in zero magnetic field and the magnetic depopulation of the four highest sub-bands is observed in a parallel orientation The relative occupations of each sub-band are deduced and their shifts with respect to E0 in magnetic field are estimated
TL;DR: Conductance fluctuations due to variable-range hopping in 1D metal-oxide-semiconductor field-effect transistors are investigated in the presence of a magnetic field and the Zeeman effect shifts the fluctuations to lower or higher chemical potentials.
Abstract: Conductance fluctuations due to variable-range hopping in 1D metal-oxide-semiconductor field-effect transistors are investigated in the presence of a magnetic field. With an increase in magnetic field, the Zeeman effect shifts the fluctuations to lower or higher chemical potentials. These shifts reflect the relative populations and occurrence of hopping from singly and doubly occupied sites. Combined with density-of-states measurements, they can provide an estimate of the intrasite Coulomb repulsion in 1D metal-oxide-semiconductor field-effect transistors. The orbital effect on conductance fluctuations is also discussed.
TL;DR: Insulating thin films of indium oxide exhibit negative, anisotropic magnetoresistance and the systematics of these results imply that the Magnetoresistance mechanism may give different weight to the distribution of the localization lengths than that given by the hopping conductivity.
Abstract: Insulating thin films of indium oxide exhibit negative, anisotropic magnetoresistance. The systematics of these results imply that the magnetoresistance mechanism may give different weight to the distribution of the localization lengths than that given by the hopping conductivity.
TL;DR: In this paper, a multi-band geometric-magnetoresistance (GMR) theory is developed in the relaxation-time approximation, and average and differential mobility expressions are defined.
Abstract: Classical magnetoresistance techniques have proven to be quite useful for obtaining mobility profiles in GaAs MESFET structures. Here we extend these techniques to AlxGa1−xAs/GaAs MODFET structures, which are more complicated because of multi-band conduction effects. A multi-band geometric-magnetoresistance (GMR) theory is developed in the relaxation-time approximation, and average and differential mobility expressions are defined. The magnetic-field dependences of these quantities permit determination of the mobilities associated with the various conducting bands. We apply this analysis to an Al0.3Ga0.7As/GaAs MODFET structure and obtain results for μ0, the lowest subband mobility, μ1–3, a combination of higher-subband mobilities, and μAlG, the mobility in the heavily doped Al0.3Ga0.7As layer. Complicating factors such as finite Hall field, energy-dependent relaxation time, parasitic resistance and gate current are also considered.