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تسجيل مستخدم جديدRoom-temperature annealing effects on the basal-plane resistivity of optimally doped YBa$_2$Cu$_3$O$_{7-delta}$ single crystals
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We reveal that the temperature dependence of the basal-plane normal-state electrical resistance of optimally doped YBa$_2$Cu$_3$O$_{7-delta}$ single crystals can be with great accuracy approximated within the framework of the model of s-d electron-phonon scattering. This requires taking into account the fluctuation conductivity whose contribution exponentially increases with decreasing temperature and decreases with an increase of oxygen deficiency. Room-temperature annealing improves the sample and, thus, increases the superconducting transition temperature. The temperature of the 2D-3D crossover decreases during annealing.
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The temperature and field dependence of reversible magnetization have been measured on a YBa$_2$Cu$_3$O$_{7-delta}$ single crystal at six different doping concentrations. It is found that the data above 2 T can be described by the scaling law based o
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We have studied the normal-to-superconducting phase transition in optimally-doped YBa$_2$Cu$_3$O$_{7-delta}$ in zero external magnetic field using a variety of different samples and techniques. Using DC transport measurements, we find that the dynami
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We report the first direct observation of the oxygen-isotope ($^{16}$O/$^{18}$O) effect on the in-plane penetration depth $lambda_{ab}$ in a nearly optimally doped YBa$_2$Cu$_3$O$_{7-delta}$ film using the novel low-energy muon-spin rotation techniqu
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We report on the scaling of transport properties around the vortex melting in YBa$_2$Cu$_3$O$_{7- delta}$ oriented-twin single crystals in applied magnetic fields between 1T and 18T. We find that for all the measured field range the linear resistivit
y scales as $rho (t,theta) sim t^{sy} {cal F}_{pm} (sin(theta)t^{-sx})$, with $t=|T-T_{BG}|$ and $theta$ the angle between de planar defects and the magnetic field. The scaling is valid only for angles where the transition temperature $T_{BG} (theta)$ shows a cusp. The critical exponents $sx$ and $sy$ are in agreement with the values predicted by Lidmar and Wallin only at magnetic fields below 4T. A change in the value of $sx$ from $sx = 1 pm 0.2$ to $sx = 3 pm 0.2$ at around $H^{cr} approx $ 4T when the magnetic field is increased, is responsible for changes in the shape of the $T_{BG} (theta)$ curve and in the dependence of the linear dissipation on temperature and angle. The results strongly suggest the existence of a different vortex glassy phase in twinned crystals compared to the Bose-glass state found in samples with linear defects.
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