Anomalous Conduction between the Band and Nearest-Neighbor Hopping Conduction Regions in Heavily Al-Doped p-Type 4H-SiC

We measure the temperature-dependent resistivity (ρ(T)) for thick heavily Al- and Ncodoped p-type 4H-SiC samples grown by chemical vapor deposition (CVD), physical vapor transport (PVT), and solution growth (SG), and investigate their conduction mechanisms. For samples with an Al concentration (CAl) of 3.5×1019 to 1×1020 cm-3 grown by CVD, PVT, and SG, the conduction mechanisms at high and low temperatures are band and nearest-neighbor hopping (NNH) conduction, respectively. In the range CAl of 1×1019 to 3.5×1019 cm-3, on the other hand, an anomalous conduction, referred to as X conduction here, is observed between the band and NNH conduction regions for the samples grown by CVD and PVT, but not those grown by SG. One of the differences between the samples grown by CVD and PVT and those grown by SG is the off-orientation toward [11-20] of the (0001) 4H-SiC substrate. We discuss the reason for the appearance of X conduction, which appears to be consistent with dopant-concentration inhomogeneity model.

Hybrid Superconducting-Ferromagnetic [Bi2Sr2(Ca,Y)2Cu3O10]0.99(La2/3Ba1/3MnO3)0.01 Composite Thick Films

We report here on the development of composite thick films exhibiting hybrid superconducting and ferromagnetic properties, produced through a low-cost, fast, and versatile process. These films were made of high Tc cuprate superconductor Bi2Sr2(Ca,Y)2Cu3O10 (with Y:Ca ratio of 5%) and ferromagnetic perovskite La2/3Ba1/3MnO3, synthesized by melting-quenching annealing process on a MgO substrate. Curie temperature for La2/3Ba1/3MnO3 was determined (~336 K ) by magnetic field assisted thermogravimetric analysis (TGA), while superconducting behavior of Bi2Sr2(Ca,Y)2Cu3O10/MgO films was observed through temperature-dependent resistance measurements. Superconducting features in our hybrid compound were corroborated by temperature-dependent resistivity and magnetic susceptibility.

Optical and electrical properties of all-inorganic Cs2AgBiBr6 double perovskite single crystals

Temperature-dependent resistivity and cathodoluminescence (CL) measurements of solution-processed Cs2AgBiBr6 double perovskite single crystals.

Enhanced Néel temperature in EuSnP under pressure

The high-pressure single crystal X-ray diffraction results for EuSnP are reported with no structural phase transition below ∼6.2 GPa. Temperature-dependent resistivity measurements up to 2.15 GPa indicate that the antiferromagnetic transition temperature (TN) is significantly enhanced under pressure.

Electrical transport and magnetoresistance of double layered CMR manganites R1.2Sr1.8Mn2O7(R = La, Pr, Sm)

Polycrystalline bulk samples of double layered (DL) colossal magnetoresistive (CMR) manganites R1.2Sr1.8Mn2O7 (R = La, Pr, Sm) were prepared by sol-gel method to study the effect of size of lanthanide ion on their magnetotransport properties. The electrical resistivity of the samples was investigated in the temperature range of 70 K to 300 K at different magnetic fields. The samples LSMO and PSMO show insulator-to-metal transition (IMT) behavior, while SSMO sample exhibits insulating behavior in the entire temperature range with a very large value of resistivity. The insulator-to-metal transition temperature (TIM) decreases from 123 K (LSMO) to 90 K (PSMO) and disappears in SSMO sample. To explain the electrical transport above TIM, the temperature dependent resistivity data (T > TIM) of all the samples were fitted to the equations of different conduction models. The results indicate that the conduction at T > TIM is due to Mott variable range hopping (VRH) mechanism in the LSMO and PSMO samples, while Efros-Shkloskii (ES) type of VRH model dominates the conduction process in the SSMO sample. All the three samples show increasing magnetoresistance (MR) even below TIM and the maximum MR is shown by LSMO (39 % at 75 K, 3 T).