Muon-spin-rotation measurements of the penetration depth in Li_2Pd_3B

Measurements of the magnetic field penetration depth $\lambda$ in the ternary boride superconductor Li$_2$Pd$_3$B ($T_c\simeq7.3$ K) have been carried out by means of muon-spin rotation ($\mu$SR). The absolute values of $\lambda$, the Ginzburg-Landau parameter $\kappa$, and the first $H_{c1}$ and the second $H_{c2}$ critical fields at T=0 obtained from $\mu$SR were found to be $\lambda(0)=252(2)$ nm, $\kappa(0)=27(1)$, $\mu_0H_{c1}(0)=9.5(1)$ mT, and $\mu_0H_{c2}(0)=3.66(8)$ T, respectively. The zero-temperature value of the superconducting gap $\Delta_0=$1.31(3) meV was found, corresponding to the ratio $2\Delta_0/k_BT_c=4.0(1)$. At low temperatures $\lambda(T)$ saturates and becomes constant below $T\simeq 0.2T_c$, in agreement with what is expected for s-wave BCS superconductors. Our results suggest that Li$_2$Pd$_3$B is a s-wave BCS superconductor with the only one isotropic energy gap.Comment: 6 pages, 7 figure

Probing the Yb3+^{3+} spin relaxation in Y0.98_{0.98}Yb0.02_{0.02}Ba2_{2}Cu3_{3}Ox_{x} by Electron Paramagnetic Resonance

The relaxation of Yb$^{3+}$ in YBa$_{2}$Cu$_{3}$O$_{x}$ ($6<x<7$) was studied using Electron Paramagnetic Resonance (EPR). It was found that both electronic and phononic processes contribute to the Yb$^{3+}$ relaxation. The phononic part of the relaxation has an exponential temperature dependence, which can be explained by a Raman process via the coupling to high-energy ($\sim$500 K) optical phonons or an Orbach-like process via the excited vibronic levels of the Cu$^{2+}$ ions (localized Slonczewski-modes). In a sample with a maximum oxygen doping $x$=6.98, the electronic part of the relaxation follows a Korringa law in the normal state and strongly decreases below $T_{c}$. Comparison of the samples with and without Zn doping proved that the superconducting gap opening is responsible for the sharp decrease of Yb$^{3+}$ relaxation in YBa$_{2}$Cu$_{3}$O$_{6.98}$. It was shown that the electronic part of the Yb$^{3+}$ relaxation in the superconducting state follows the same temperature dependence as $^{63}$Cu and $^{17}$O nuclear relaxations despite the huge difference between the corresponding electronic and nuclear relaxation rates.Comment: 8 pages, 6 figure

An Analytical Model for Calculation of the Steel Hardness after Continuous Cooling

A number of modern engineering steel grades were analyzed using the CCT diagrams plotted by means of the dilatometer. The statistical analysis of the experimental data allowed for the determination of the equations connecting the critical cooling rate to achieve fully martensitic microstructure and the martensite hardness with the chemical composition of the steel. The dependence of the steel hardness on the cooling rate in the range of 0.1...30 C/s was determined. It was shown that this dependence had the logarithmic character for every studied steel grade. The equations connecting the coefficients of the logarithmic function with the chemical composition of steel were obtained. © Published under licence by IOP Publishing Ltd.The work was supported by the Act 211 of Government of the Russian Federation, contract № 02.A03.21.0006, the Ministry of Science and Higher Education of the Russian Federation, project №11.1465.2014/K, and by the state assignment of the M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, theme “Laser”

Nodeless superconductivity in the infinite-layer electron-doped Sr_0.9La_0.1CuO_2 cuprate superconductor

We report on measurements of the in-plane magnetic penetration depth \lambda_{ab} in the infinite-layer electron-doped high-temperature cuprate superconductor Sr_0.9La_0.1CuO_2 by means of muon-spin rotation. The observed temperature and magnetic field dependences of \lambda_{ab} are consistent with the presence of a substantial s-wave component in the superconducting order parameter in good agreement with the results of tunneling, specific heat, and small-angle neutron scattering experiments.Comment: 6 pages, 5 figure

Dilatometric Research of Cr–Ni–Mo Steels during Isothermal Treatment

В проведенной работе дилатометрическим методом были исследованы Cr-Ni-Mo сталь исходного состава, а также стали с добавлением алюминия и кремния. Определены структура сталей в ходе изотермической обработки, а также влияние на структуру алюминия и кремния.In this work, Cr–Ni–Mo steel of the initial composition and alloyed with aluminum and silicon were investigated by the dilatometric method. The structure of steels during isothermal treatment, as well as the effect on the structure of aluminum and silicon, have been determined

Mixed order parameter symmetries in cuprate superconductors

The recent observation of an inflection point in the temperature dependence of the in-plane magnetic field dependence (lambda_ab) is investigated within a two-band model with coupled order parameters of different symmetries. While the dominant order parameter has d-wave symmetry, the smaller one is of s-wave symmetry. Superconductivity is robust in the d-wave channel and induced via interband interactions in the s-wave subsystem.Comment: 10 pages, 4 figure

Oxygen isotope effect on superconductivity and magnetism in Y_1-xPr_xBa_2Cu_3O_7-\delta

Oxygen isotope (^{16}O/^{18}O) effects (OIE's) on the superconducting transition (T_c), the spin-glass ordering (T_g), and the antiferromagnetic ordering (T_N) temperatures were studied for Y_1-xPr_xBa_2Cu_3O_7-\delta as a function of Pr content (0.0\leq x \leq 1.0). The OIE on T_c increases with increasing x up to x\approx0.55, where superconductivity disappears. For decreasing x the OIE's on T_N and T_g increase down to x\approx 0.7 where antiferromagnetic order and down to x\approx0.3 where spin-glass behavior vanish, respectively. The OIE's on T_g and T_N are found to have {\it opposite signs} as compared to the OIE on T_c. All OIE's are suggested to arise from the isotope dependent mobility (kinetic energy) of the charge carriers.Comment: 5 pages, 3 figures, 1 tabl

Effect of Heat Treatment on Microstructure and Properties of High-Strength Steel

Изучены особенности структурообразования в стали 30Х2ГСН2ВМ (ВЛ-1) при реализации различных режимов изотермической обработки: ступенчатая закалка при температуре ниже Мн (quenching-partitioning), изотермическая закалка на бейнит. Показано, что расчетная оптимальная температура ступенчатой закалки не обеспечивает предсказанное количество стабильного остаточного аустенита в структуре исследуемой стали.The microstructure formation in steel 30Kh2GSN2VM are studied after the isothermal treatment: quenching-partitioning, austempering. It is shown that the calculated partitioning temperature does not provide the predicted amount of stable retained austenite in the structure of the steel under study.Исследование выполнено за счет средств гранта Российского научного фонда 22-29-00106.The research was carried out at the expense of the grant of the Russian science foundation 22-29-00106

The Effect of the Tempering Temperature on the Mechanical Properties of the Novel High Strength Steel

The novel high strength steel with high hardenability was studied. The temperature ranges of the austenite transformation were determined. The microstructure and the mechanical properties of the steel under consideration were investigated after the oil quenching and tempering at 200…600 °C.Исследована высокопрочная сталь, обладающая высокой устойчивостью переохлажденного аустенита к превращению по первой ступени. Установлены температурные интервалы превращений при непрерывном нагреве и охлаждении. Исследована микроструктура и определены механические свойства стали после закалки в масле и отпуска в интервале 200…600 °C