论文标题
来自兴奋剂haldane链和梯级梯子的配对密度波超导体
Pair-density-wave superconductor from doping Haldane chain and rung-singlet ladder
论文作者
论文摘要
我们报告了掺杂（i）旋转的haldane链或（ii）在rung singlet阶段的两腿梯子中，掺杂的数值发现了成对密度波（PDW）超导体，其中掺杂量均占据了单腿。我们使用广义近藤模型对这些系统进行建模。巡回电子由$ t-j $型号进行了关联和描述，并通过kondo耦合$ j_k $进一步与旋转$ 1/2 $ HEISENBERG型号相连。当电子的密度$ x $是一个时，莫特绝缘子处于haldane阶段或rung singlet阶段，具体取决于$ j_k $是负数还是正面。掺杂后，带有$ \ mathbf q =π$的配对密度波可以出现，这两个符号的$ j_k $。在$ j_k \ rightarrow - \ infty $限制中，该模型还原为最近提出的II型T -J模型，我们观察到PDW超导体和非常规的Luttinger液体相之间的连续过渡与掺杂。我们还确定了超导体的复合阶参数，该参数可以理解为由两个附近的费米子旋转核酸杆菌形成的库珀对。我们的模型和预测的PDW相可以通过在固态系统中由Ni $^{2+} $形成的掺杂s = 1链，或者在固态系统中形成的链条或两腿在腿之间具有潜在偏见的两腿梯子来实验实现，这优先将载流子掺入单腿。
We report the numerical discovery of a pair-density-wave (PDW) superconductor from doping either (i) a spin-one Haldane chain or (ii) a two-leg ladder in the rung singlet phase in which the doped charges occupy a single leg. We model these systems using a generalized Kondo model. The itinerant electrons are correlated and described by the $t-J$ model, and are further coupled to a spin $1/2$ Heisenberg model through the Kondo coupling $J_K$. When the density of electrons $x$ is one, the Mott insulator is in a Haldane phase or in a rung singlet phase depending on whether $J_K$ is negative or positive. Upon doping, a pair-density-wave with $\mathbf Q=π$ can emerge for both signs of $J_K$. In the $J_K \rightarrow -\infty$ limit, the model reduces to the recently proposed type II t-J model and we observes a continuous transition between the PDW superconductor and an unconventional Luttinger liquid phase with doping. We also identify a composite order parameter for the superconductor, which can be understood as a Cooper pair formed by two nearby fermionic spin-polarons. Our model and the predicted PDW phase can be experimentally realized by doping S=1 chains formed by Ni$^{2+}$ in a solid state system or a two-leg ladder of fermionic cold atoms with a potential bias between legs, which preferentially dopes carriers into a single leg.
