B. S. de Lima

Procedure for measuring electrical resistivity of anisotropic materials: A revision of the Montgomery method

A procedure for determining the electrical resistivity of anisotropic materials is presented. It offers several improvements to the well-known Montgomery method. One improvement, in particular, is the ability to obtain the electrical resistivity for all three axes of an orthorhombic crystal analytically, rather than using the iterative approach suggested by Montgomery for the third axis. All necessary equations are derived and their application in determining the tensor components of the electrical resistivity is explained in detail. Measurements on isotropic specimens were executed in order to test the foundations of the method. Measurements on anisotropic samples are compared with measurements obtained by using the standard four-probe method, revealing good agreement.

Superconductivity and magnetism in the KxMoO2−δ

Coexistence between superconductivity and magnetism is reported for the KxMoO2−δ samples. Photoemission experiments show that the presence of Mo3+ ions is responsible for the weak ferromagnetic ordering observed in the KxMoO2−δ samples. Magnetic ordering temperature and superconducting critical temperature (TC) ratio range from 7 to 18 in this compound. These are the highest ratios reported so far for a magnetic superconductor. TC decreases with increasing potassium composition (x). For the first time, TC near 10 K is reported in the K-Mo-O system.

Interplay between antiferrodistortive, ferroelectric, and superconducting instabilities in Sr1-x Ca-x TiO3-delta

SrTiO

Ta1-xHfxB: A new FeB-prototype superconductor

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Phase transitions in K-doped MoO2

undergoes a cubic-to-tetragonal phase transition at 105K. This antiferrodistortive transition is believed to be in competition with incipient ferroelectricity. Substituting strontium by isovalent calcium induces a ferroelectric order. Introducing mobile electrons to the system by chemical non-isovalent doping, on the other hand, leads to the emergence of a dilute metal with a superconducting ground state. The link between superconductivity and the other two instabilities is an open question, which gathers momentum in the context of the growing popularity of the paradigm linking unconventional superconductors and quantum critical points. We present a set of specific-heat, neutron-scattering and dielectric permittivity and polarization measurements on Sr

Properties and superconductivity in Ti-doped NiTe2 single crystals

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Electrical Resistivity in Non-stoichiometric MoO2

Ca

Evidence for topological behavior in superconducting CuxZrTe2-y

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Ta5GeB2: New T2 superconductor phase

TiO

Unusual superconducting behavior in HfV 2 Ga 4

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