The flux motion and the symmetry of the Cooper pairs in a high-Tc superconductors

Single crystals of the representative high-Tc superconductor YBa-D22-D23-D2O-D27-D2 are usually twinned。双胞胎边界阻止了我们从材料的内在物理性质中学习。On the other hand， it is known that （Ca，La，Ba）y D23 y D2O y D2（CLBCO） and NdBaSrCu D23 y D2（NBSCO） among the 1-2-3 type superconductors are tetragonal in the crystal structure。因此，超级传导这些化合物的单一晶体必须是双胞胎的。我们已经通过旅行溶剂浮动区方法研究了CLBCO和NBSCO的单晶体增长率，以获得1-2-3型超级导体的原始双晶体。Trying various kinds of solvent， we have succeeded in obtaining single crystals with the dim\of the order of 1×1× 0. 5 mmイイD113イエD1。CLBCO和NBSCO的单一晶体是四重和非超级导电。通过氧化物中的退火，CLBCO的单个晶体成为Tc=55 - 65的超级导体 ... More K：保持四角结构。关于另一方，NBSCO的单一晶体已经从四角变成其他人，通过氧化物中的退火，though they have be\ome superconductor with Tc = 55 K. Spin gap of Sry D214 y D224 y D2O y D241 y D2studied by the thermal conductivity。layered cuprate Sr D214 y D2Cu D224 y D241 y D2 consisting of two-D22/D23/D2ladder planes （regarded as a spin-1/2 ladder system with two legs） and one-D22/D22/D2/ Carrier-doped spin ladder systems Sry D214-x y D2A y D2x y D224 y D2O y D241 y D2 （A=Ca，La） have attracted great interest， triggered by the theoretical prediction on the spin gap and superconductivity。我们从热行为测量中调查了旋转间隙和在梯子上的洞配对，并从预测的理论上找到了两种旋转兴奋。观察到的热行为κ has been analyzed to be composed of κ D2 phyD 2，κ D2 spin D2 and κ D2 hole D2 due to phonons， spins and holes， respectively。The spin gap in the ladder estimated from D2 spin D2 is ~ 400 K and independent of x（Ca）。这被归类为对从自旋-单曲到自旋-三重奏的兴奋进行相应的排序，作为中子散射的估计。The spin gap estimated from D2 hole D2 decreases with increasing x（Ca）。这被归类为旋转单对的争论，命名为洞对的争论，根据核磁共振测量的那些估计。Less（低）

Single crystals of the representative high-Tc superconductor YBaィイD22ィエD2CuィイD23ィエD2OィイD27ィエD2 are usually twinned. The twin boundaries prevent us from studying the intrinsic physical properties of the material. On the other hand, it is known that (Ca,La,Ba)ィイD23ィエD2CuィイD23ィエD2OィイD2yィエD2(CLBCO) and NdBaSrCuィイD23ィエD2OィイD2yィエD2(NBSCO) among the 1-2-3 type superconductors are tetragonal in the crystal structure. Therefore, superconducting single-crystals of these compounds must be twin-free. We tried the single-crystal growth of CLBCO and NBSCO by the travelling-solvent floating zone method to obtain originally twin-free single-crystals of the 1-2-3 type superconductors. Trying various kinds of solvent, we have succeeded in obtaining single crystals with the dimensions of the order of 1×1×0.5mmィイD113ィエD1. As-grown single-crystals of CLBCO and NBSCO are tetragonal and non-superconducting. Through the annealing in oxygen, single crystals of CLBCO have became superconductors with Tc=55 - 65 … More K, keeping the tetragonal structure. On the other hand, single crystals of NBSCO have changed from tetragonal to orthorhombic through the annealing in oxygen, though they have become superconductor with Tc = 55 K.Spin gap of SrィイD214ィエD2CuィイD224ィエD2OィイD241ィエD2 studied by the thermal conductivity.The layered cuprate SrィイD214ィエD2CuィイD224ィエD2OィイD241ィエD2 consisting of two-dimensional CuィイD22ィエD2OィイD23ィエD2 ladder planes (regarded as a spin-1/2 ladder system with two legs) and one-dimensional CuOィイD22ィエD2 chains. The carrier-doped spin ladder systems SrィイD214-xィエD2AィイD2xィエD2CuィイD224ィエD2OィイD241ィエD2 (A=Ca,La) have attracted great interest, triggered by the theoretical prediction on the spin gap and superconductivity. We have investigated the spin gap and the hole pairing in the ladder from the thermal conductivity measurement and found two kinds of spin excitation as predicted theoretically. The observed thermal conductivity κ has been analyzed to be composed of κィイD2phィエD2, κィイD2spinィエD2 and κィイD2holeィエD2 due to phonons, spins and holes, respectively. The spin gap in the ladder estimated from κィイD2spinィエD2 is 〜400K and independent of x(Ca). This is regarded as corresponding to the excitation from spin-singlet to spin-triplet, as those estimate from the neutron scattering. The spin gap estimated from κィイD2holeィエD2 decreases with increasing x(Ca). This is regarded as corresponding to the dissociation of spin-singlet pairs, namely, the dissociation of hole pairs, as those estimate from the NMR measurements. Less