78 research outputs found
Scientific, institutional and personal rivalries among Soviet geographers in the late Stalin era
Scientific, institutional and personal rivalries between three key centres of geographical research and scholarship (the Academy of Sciences Institute of Geography and the Faculties of Geography at Moscow and Leningrad State Universities) are surveyed for the period from 1945 to the early 1950s. It is argued that the debates and rivalries between members of the three institutions appear to have been motivated by a variety of scientific, ideological, institutional and personal factors, but that genuine scientific disagreements were at least as important as political and ideological factors in influencing the course of the debates and in determining their final outcome
Hall effect in the vicinity of quantum critical point in Tm1-xYbxB12
The angular, temperature and magnetic field dependences of Hall resistance
roH for the rare-earth dodecaboride solid solutions Tm1-xYbxB12 have been
studied in a wide vicinity of the quantum critical point (QCP) xC~0.3. The
measurements performed in the temperature range 1.9-300 K on high quality
single crystals allowed to find out for the first time in these fcc compounds
both an appearance of the second harmonic contribution in ro2H at QCP and its
enhancement under the Tm to ytterbium substitution and/or with increase of
external magnetic field. When the Yb concentration x increases a negative
maximum of a significant amplitude was shown to appear on the temperature
dependences of Hall coefficient RH(T) for the Tm1-xYbxB12 compounds. Moreover,
a complicated activation type behavior of the Hall coefficient is observed at
intermediate temperatures for x>0.5 with activation energies Eg~200K and
Ea~55-75K in combination with the sign inversion of RH(T) at low temperatures
in the coherent regime. The density of states renormalization effects are
analyzed within the variation of Yb concentration and the features of the
charge transport in various regimes (charge gap formation, intra-gap manybody
resonance and coherent regime) are discussed in detail in Tm1-xYbxB12 solid
solutions.Comment: 38 pages including 10 figures, 70 reference
Determination of the Degree of Homogeneity for n-Ge Crystals by Measurements of Magnetoresistance in Classically Weak Magnetic Fields
In a wide range of values of the resistivity 0.0212 £ r £ 35 Ohm×cm for n-Ge crystals with known crystallographic orientation the ratio M100 2 100 1 M100 2 1 M110 110 M110 º = º , which was predicted by the theory, was experimentally confirmed. The experimentally measured deviations from the relationship M100 2 1 M110 = , which are associated with the heterogeneity of the crystals, it is proposed to use for qualitative assessment of the degree of heterogeneity in the spatial distribution of dopants in the samples. Keywords: germanium, degree of homogeneity, resistivity, magnetic field, magnetoresistance
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