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ABSTRACT: We measured the transverse angular magnetoresistance and the Hall effect on high-quality NbSi2 single crystals at low temperatures (4.2 K ≤ T ≤ 160 K) and high magnetic fields (B ≤ 20 T). The material behaves like a compensated metal, i.e. the magnetoresistance grows generally proportionally to B2. For some current–field configurations, however, saturation of the magnetoresistance occurs, giving evidence for the presence of an open orbit on the Fermi surface of NbSi2 parallel to the c axis. The Hall coefficient shows, as does the magnetoresistance, a low-field–high-field transition. It varies between −3.5 and −4.5 × 1010 m3 C−1 in low magnetic field to −10.5 × 10−10 m3 C−1 in the high-field region. We compare our results with those obtained for NbSi2 thin films and discuss the validity of parameters deduced from transport data.
Journal of Physics Condensed Matter 07/2002; 14(29):7007. · 2.55 Impact Factor
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ABSTRACT: We report magnetic susceptibility measurements on single crystals of very-high-purity VSi2, NbSi2 and TaSi2 from 4 K to room temperature. VSi2 is paramagnetic while NbSi2 and TaSi2 are diamagnetic. A systematic anisotropy of chi is observed for the three compounds. The results are in good agreement with previous investigations of the electronic properties of these materials. The different contributions of chi which account for these data are discussed.
Journal of Physics Condensed Matter 12/1998; 5(46):8755. · 2.55 Impact Factor
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ABSTRACT: The authors report magnetic and resistivity measurements between 2 and 300 K on well characterised CeSix single crystals (x=1.71 and 1.86). Both the magnetic and the transport properties of this ferromagnetic dense Kondo system are strongly anisotropic. They compare the resistivity results with those of NdSi1.7 which crystallises with the same structure and exhibits a simpler magnetic behaviour. An anomaly is observed at high temperatures (230 K and 260 K respectively for x=1.71 and x=1.86) in the resistivity of CeSix which could result from some structural mechanism.
Journal of Physics Condensed Matter 12/1998; 2(2):431. · 2.55 Impact Factor
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Materials for Advanced Metallization, 1997. MAM '97 Abstracts Booklet., European Workshop; 02/1998
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ABSTRACT: We present phonon measurements carried out on NbSi<sub>2</sub>, TaSi<sub>2</sub> and VSi<sub>2</sub>, using neutron inelastic scattering and Raman spectroscopy in comparison with phonon properties previously investigated by other techniques: the Debye temperature values obtained from low temperature specific heat and resistivity measurements and the phonon spectra issued from point-contact spectroscopy
Materials for Advanced Metallization, 1997. MAM '97 Abstracts Booklet., European Workshop; 04/1997
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ABSTRACT: We report measurements of Hall effect, transverse magnetoresistance, and specific heat on high-quality TiSi2 (C54 phase) single crystals at low temperatures. We used crystals with low residual resistivity (typically ρ4.2 K=0.15 μΩ cm) and magnetic fields (B) up to 20 T. These facts allowed us to study the electronic properties from the low (ωcτ≪1) to the high field regime (ωcτ≳1, ωc=eB/m* being the cyclotron frequency and τ the electron relaxation time) as a function of magnetic-field strength and temperature. The low field Hall coefficient RH is negative, almost constant RH=-(0.5±0.1)×10-10 m3/C between 100 and 300 K and it changes sign at ∼30 K. The angular dependence of magnetoresistance shows either minima or maxima when the magnetic field is parallel to the principal crystallographic axes. These structures are, however, less pronounced than in other silicides, such as PdSi2 and NbSi2, and this suggests only a weak anisotropy of the TiSi2 Fermi surface. The galvanomagnetic properties behave consistently with band-structure calculations of Mattheiss and Hensel [Phys. Rev. B 39, 7754 (1989)] who found that TiSi2 is a compensated metal with only closed orbits for the Fermi electrons. Using a simple two-band model we estimated, from the low field magnetoresistance, carrier density ne=nh=(0.45–0.52)×1022 cm-3 assuming equal concentration of electrons and holes. Low temperatures (1.6<T<22 K) specific-heat (Cp) measurements fit a linear Cp/T=γ+βT2 dependence, with γ=3.35±0.05 mJ/K2 mol and β=0.0201±0.0005 mJ/K4 mol. From these parameters we estimated the Debye temperature ΘD=662±4 K and the renormalized electronic density of states at the Fermi surface N(ɛF)(1+λ)=2.85 states/eV cell. © 1996 The American Physical Society.
Phys. Rev. B. 09/1996; 54(11).
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ABSTRACT: We investigated some structural and transport properties of semiconducting ReSi 2-δ . In the literature this silicides is reported to crystallize in an orthorhombic structure and to be stoichiometric ReSi 2 . Our investigations clearly show that the stable composition is ReSi 1.75 crystallizing in the space group P1. Transport measurements show thermally activated behavior at high temperatures with one (or two) energy gap E g =0.16 (0.30 eV). We also report Hall‐effect measurements on this material: we found that R H is positive between 30 and 660 K and at room temperature the Hall number n H =1/eR H is equal to 3.7×10<sup>18</sup> cm<sup>-3</sup>. The Hall mobility at room temperature is relatively high (μ H =370 cm<sup>2</sup>/V s) for a single crystal. © 1995 American Institute of Physics.
Journal of Applied Physics 10/1995; · 2.17 Impact Factor
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ABSTRACT: We present the magnetoresistivity at high magnetic field measured on single crystals of Pd2Si of very good quality. The magnetoresistance depends on the orientation of field and current directions relative to the crystallographic axis. It shows that this suicide behaves like a compensated metal (i.e. equal numbers of electrons and holes) with open orbits along the main crystallographic directions.
Journal of Low Temperature Physics 05/1994; 95(5):835-848. · 1.19 Impact Factor
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ABSTRACT: We present low temperature specific heat measurements of VSi2, NbSi2 and TaSi2. The three disilicides crystallize in the same hexagonal structure (C40, space group P6222). The measured values of the electronic Density of States at the Fermi Energy,D(EF), are in good agreement with theoretical band structure calculations. The obtained Debye temperatures vary asM
–1/2 (M is the molar mass of the compound), showing that the interatomic forces are similar in the three disilicides. NbSi2 and TaSi2 are found to be superconductors at 0.130K and 0.353K respectively. The variation of the transition temperatures is discussed.
Journal of Low Temperature Physics 01/1993; 92(5):335-351. · 1.19 Impact Factor
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ABSTRACT: We present measurements of the magnetoresistance up to 20 teslas from 2 K to room temperature on a CeSi1.86 single crystal. This alloy behaves as an anisotropic Kondo lattice where strong ferromagnetic correlations are dominant. We observe a clear relationship between the magnetotransport and the magnetic susceptibility of this compound.
Journal of Low Temperature Physics 10/1990; 81(3):171-178. · 1.19 Impact Factor
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ABSTRACT: The electrical resistivity of monocrystalline TiSi 2 , TaSi 2 , MoSi 2 , and WSi 2 has been measured from 4.2 to 1100 K. These disilicides are metallic, yet there is a remarkable difference in the temperature dependence of their intrinsic resistivities. TiSi 2 and TaSi 2 are found to exhibit a T<sup>5</sup> dependence in the temperature range of 13≪T≪30 K and 15≪T≪28 K, respectively, while MoSi 2 and WSi 2 show a T<sup>3.8</sup> dependence from 15 to 40 K. For TiSi 2 , along the three crystallographic directions 〈100〉, 〈010〉, and 〈001〉, the phonon contribution to the resistivity was found to be linear in temperature above 300 K. The same behavior was observed for TaSi 2 along the 〈0001〉 axis, while a negative deviation from the linearity followed by a quasisaturation was observed with the current, parallel to the 〈101¯0〉 axis. The resistivity data of WSi 2 and MoSi 2 with the current parallel to 〈001〉 and 〈110〉 crystallographic directions showed a positive deviation from linearity. The data are fitted to several theoretical expressions at low temperatures and in the full range of temperatures. The results are discussed in light of these theories.
Journal of Applied Physics 03/1989; · 2.17 Impact Factor
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ABSTRACT: We report on the superconducting properties of a series of sputtered, amorphous Zr100–x
Cux (19x48) alloys. From the thermodynamic parameters, we conclude that there is a very good agreement with the BCS theory on the high-Cu-concentration side. When Zr content increases, and then the coupling strength, a very continuous and progressive deviation from the BCS limit occurs, which is in rather good agreement with theoretical predictions for crystalline alloys. However, a departure develops at high Zr concentration. Despite the surprising behavior of the electronic density of states N(E
F) characteristic of these highly disordered alloys, a correlation is found between N(E
F) and the Ginzburg-Landau parameter .
Journal of Low Temperature Physics 01/1987; 69(3):189-201. · 1.19 Impact Factor
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ABSTRACT: High-frequency point-contact spectroscopy as well as conventional low-frequency PC spectroscopy has been used for determining the spectral functions of the electron-phonon interaction (EPI) for three disilicides TiSi2, TaSi2, and VSi2. The temperature dependences of resistivity have been calculated from obtained EPI functions. Comparison of calculated dependences with known experimental data allowed correction of the electron-phonon interaction constants for the studied disilicides.
Journal of Low Temperature Physics, v.129, 105-116 (2002).
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ABSTRACT: A single crystal of MnSi2−x was obtained by a modified Czochralski pulling technique in a cold copper crucible. The quality and the nature of the sample were checked by an accurate crystal structure determination, which revealed the sample to be Mn4Si7. Resistivity and magnetic measurements were performed on this sample in the temperature range between 2 K and room temperature and in magnetic fields up to 7.5 T. Mn4Si7 shows a metallic behaviour and the good crystal quality was revealed by the high residual resistance ratio of 360. For the magnetic susceptibility we observed a Curie–Weiss law above about 40 K with a low effective moment of peff=0.365 μB/Mn. Below this temperature, moments order in an anisotropic helical state, and in fields above 1 T, they align with a saturation moment of psat=0.012 μB/Mn. Mn4Si7 is a weak itinerant magnetic system that could be a good candidate for the observation of the critical quantum fluctuations expected for marginal Fermi liquids.
Journal of Alloys and Compounds.
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ABSTRACT: Single crystals of MoSi2 with very high resistivity ratios have been grown using a Crochralski technique and a modified Hukin-type crucible. Thermal expansion coefficient and resistivity have been measured as a function of temperature and are found anisotropic. The resistivity ratio ϱ(293 K)/ϱ(4.2 K) = 1760 is extremely high in this class of compounds.
Solid State Communications.
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ABSTRACT: We investigated the electronic transport properties and the magnetic susceptibility of the semiconducting silicide ReSi1.75. This compound crystallises in a monoclinic structure (space group P1). The resistivity of this silicide is anisotropic depending on the direction of the current flow. At high temperatures we observe thermally activated behaviour for the resistivity with one (or two) energy gap(s) Eg = 0.16 eV (0.30 eV). Hall effect measurements yield a positive Hall coefficient in the temperature range between 30 and 660 K. At room temperature we found a Hall carrier concentration of 3.7 × 1018 cm−3 and a quite high Hall mobility of 370 cm2/V · s. As the resistivity, the magnetic susceptibility of ReSi1.75 is anisotropic depending on the orientation of the magnetic field relative to the crystallographic axes. At room temperature χ is strongly diamagnetic. Below about 50 K, χ increases with decreasing temperature.
Applied Surface Science 91:82-86. · 2.10 Impact Factor
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ABSTRACT: The phonon spectra of metallic disilicides VSi2, NbSi2, and TaSi2 have been studied in detail by inelastic neutron scattering at 300 K and specific heat measurements between 10 K and 250 K. The specific heat calculated from the generalised phonon density of states extracted from neutron measurements is in good agreement with the measured lattice contribution to the specific heat. The properties of the phonon spectra are discussed in relation with other data reported for these isostructural and isoelectronic disilicides.
Solid State Communications 126(7):415-419. · 1.65 Impact Factor
