论文标题
在准二维超导体中，垂直单轴压力引起的遗传范霍夫奇异性和高温超导阶段
Vestigial Van Hove singularity and higher-temperature superconducting phase induced by perpendicular uniaxial pressures in quasi-two-dimensional superconductors
论文作者
论文摘要
我们在垂直于导电层的单轴压力下（以下称为垂直压力）检查了半填充的准二维超导体。自然的猜想是，垂直压力会降低TC，因为它增加了层间跳的能量T_z，这会削弱由于二维范·霍夫（Van Hove Hove）奇异性而导致的对数状态密度的对数增强。结果表明，与这种猜想相反，垂直压在降低TC之前的系统中可以显着增强TC的TC，并且增强的强度显着取决于配对对称性。当d，d'，cz和sz的索引定义为基础函数cos k_x-cos k_y，sin k_x sin sin k_y，cos k_z和sin k_z时，这表明，对于s-，d-，d-，cz-和cz-d-wave配对而言，s-，d-，d-，cz-和tc急剧增加了T_Z附近的T__ Z Z附近的cus t__ Z Z Z Z附近的T_____。另一方面，对于P-，CZ-P-，SZ-P-和D'-Wave配对，TC几乎不受TZ的影响。对于SZ-和SZ-D波配对，TC表现出宽阔而弱的峰值。 TC的增强是该州最大的，也是D-Wave配对和Interlayer Singlet（CZ-WAVE）配对的第二大。这些结果可能解释了垂直压力下SR2RUO4的最新观察结果。理论和实验结果之间的比较表明，包括手性状态在内的P-，CZ-P-和SZ-P波状态以及D'-Wave状态是最有可能的固有1.5-K相的候选者，并且D-k-d-和cz-wave状态是由per per per per per per per per per perpers诱导的最有可能的候选者。 CZ-P-和SZ-P波状态分别是层间三重层和层间单线P波状状态，分别具有水平线节点。
We examine quasi-two-dimensional superconductors near half-filling under uniaxial pressures perpendicular to conductive layers (hereafter called perpendicular pressures). It is a natural conjecture that the perpendicular pressure decreases Tc because it increases the interlayer electron hopping energy t_z, which weakens the logarithmic enhancement in the density of states due to the two-dimensional Van Hove singularity. It is shown that, contrary to this conjecture, the perpendicular pressure can significantly enhance Tc in systems off half-filling before it decreases Tc, and the strength of the enhancement significantly depends on the pairing symmetry. When the indices d, d', cz, and sz are defined for the basis functions cos k_x - cos k_y, sin k_x sin k_y, cos k_z, and sin k_z, respectively, it is shown that for s-, d-, cz-, and cz-d-wave pairing, Tc steeply increases with increasing t_z near a cusp at a certain value of t_z. On the other hand, for p-, cz-p-, sz-p-, and d'-wave pairing, Tc is almost unaffected by tz. For sz- and sz-d-wave pairing, Tc exhibits a broad and weak peak. The enhancement in Tc is the largest for this state and the second largest for the d-wave pairing and interlayer singlet (cz-wave) pairing. These results may explain recent observations in Sr2RuO4 under perpendicular pressures. A comparison between the theoretical and experimental results indicates that the p-, cz-p-, and sz-p-wave states, including chiral states, and the d'-wave state are the most likely candidates for the intrinsic 1.5-K phase, and the d-, cz-d-, and cz-wave states are the most likely candidates for the 3-K phase induced by the perpendicular pressure. The cz-p- and sz-p-wave states are interlayer triplet and interlayer singlet p-wave states with horizontal line nodes, respectively.
