Механизмы, определяющие гистерезис магнитосопротивления гранулярного ВТСП в присутствии парамагнитного вклада, на примере HoBa-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-7-delta-=/SUB=-

The hysteretic magnetoresistance of granular high-temperature superconductor (HTSC) HoBa2Cu3O7-δ is investigated. Superconductors of the YBCO family with magnetic rare earth elements (Nd, Ho, Er, Sm, Yb, Dy) in place of yttrium are characterized by a significant paramagnetic contribution to the total magnetization. Impact of this paramagnetic contribution on the magnetotransport properties is analyzed using the concept of an effective field in an intergranular medium. Lines of magnetic induction from paramagnetic moments do not concentrate in intergranular boundaries, and, thus, have an insignificant effect on magnetotransport properties of granular HTSC. At the same time, there are strong concentration of magnetic flux in the intergranular boundaries due to Meissner currents and Abrikosov vortices. This magnetic flux compression determines the magnetotransport properties of granular HTSCs, including YBCO with magnetic rare earth elements.

Вклад кластеров железа в магнитные свойства сплавов Pb-=SUB=-1-y-=/SUB=-Fe-=SUB=-y-=/SUB=-Te

The field dependences of the magnetization (temperatures T = 2.0–70 K, magnetic fields B ≤ 7.5 T) of the samples from a single-crystalline Pb_1 – y Fe_ y Te ingot ( y = 0.02) grown by the Bridgman method are studied. It is established that the sample magnetization contains several major contributions such as the paramagnetism of iron ions, diamagnetism of the crystal lattice, and the contributions of charge carriers and clusters of iron atoms. The field dependences of the paramagnetic contribution of iron ions and the contribution of clusters of iron atoms are approximated by theoretical dependences based on the Brillouin and Langevin functions, respectively. The average concentrations and magnetic moment of clusters as well as the total magnetic momentum of clusters in the volume unit in the samples upon increasing the impurity concentration along the ingot are determined.

Theoretical analysis of NMR shieldings in XSe and XTe (X = Si, Ge, Sn and Pb): the spin-rotation constant saga

How the electronic contribution to the spin-rotation constant is close to the paramagnetic contribution of the NMR absolute shielding constant?

Carbon-Based Magnetic Nanocomposite Prepared by Arc-Evaporation of Sm/Co/C System

Magnetic nanocomposite of Sm/Co/C-system is prepared and characterized. It reveals chemical and thermal stability. SQUID magnetometry is applied to study hysteresis behaviour of the material. Modified Langevin formalism is used to distinguish between ferromagnetic and paramagnetic contribution to magnetization. It is shown that 80 % of low temperature remanence is stable at 350 K and coercive field at this temperature is 140 Oe.