标题： 全息超流体中非线性项导致的负磁化率引起的局部热力学不稳定性的研究 显示英文标题

标题： The local thermodynamic instability from negative susceptibility in a holographic superfluid with nonlinear terms

摘要： 在探针极限下，研究了有限超流速度下全息超流模型的电荷磁化率的局部热力学稳定性。 先前的研究表明，在超流速度超过一定值之后，巨正则系综中的超流相变变为一级相变。 我们进一步揭示在正则系综中，超流相变仍然是二级相变，这种差异表明存在一个磁化率负值的区域，这意味着在此超流速度之后出现局部热力学不稳定。 然而，我们在更大的超流速度下也遇到了“风洞”行为，这使得相图变得更加复杂。 我们进一步研究了两个非线性项$\lambda|\psi|^4$和$\tau|\psi|^6$在参数$\lambda$和$\tau$的影响下对凝聚曲线的作用，并设定了适当的$\lambda$和$\tau$值以在正则系综中消除“风洞”区域，从而得到一个更优雅的相图，并更好地表示这种不稳定的区域，这可能用于实现涡旋和量子湍流的自发形成。 显示英文摘要

摘要： The local thermodynamic stability from the charge susceptibility of a holographic superfluid model at finite superfluid velocity is studied in the probe limit. Previous studies show that beyond a finite value of the superfluid velocity, the superfluid phase transition in the grand canonical ensemble becomes first order. We further reveal that in the canonical ensemble, the superfluid phase transition is still second order, and the difference indicates a section with negative susceptibility which means local thermodynamic instability beyond this superfluid velocity. However, we also meet the ``cave of wind'' behavior at larger superfluid velocity which complicate the phase diagram. We further study the influence of the two nonlinear terms $\lambda|\psi|^4$ and $\tau|\psi|^6$ with parameters $\lambda$ and $\tau$ on the condensate curves, and set appropriate values of $\lambda$ and $\tau$ to remove the "cave of wind" region in the canonical ensemble to get a more elegant phase diagram and better represent the region with such instability, which is possible to be used to realize spontaneous formation of vortexes and quantum turbulence.