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arXiv 1812.08064cond-mat.quant-gas
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二维偶极费米子混合体:状态方程和磁相

Two-dimensional Mixture of Dipolar Fermions: Equation of State and Magnetic Phases

Tommaso Comparin, Raul Bombin, Markus Holzmann, Ferran Mazzanti, Jordi Boronat, Stefano Giorgini

摘要:

我们研究了零温度下两维费米子偶极子的两组分混合物,通过一个纯粹的排斥$1/r^3$势相互作用。当超冷原子或分子的偶极矩沿垂直于平面的约束方向排列时,该模型可以用它们来实现。我们通过扩散蒙特卡罗技术来表征非极化混合物。计算状态方程,我们确定了制度的有效性的平均场论的基础上的低密度扩展和比较我们的结果与硬盘模型的排斥费米子。在高密度下,我们讨论了巡游铁磁性的可能性,即基态是否可以在流体相中完全极化。在固定节点近似,我们表明,准确的Jastrow-Slater试验波函数,即使与典型的两体回流校正,是不足以解决相关的能量差异。利用迭代-回流改进的试探波函数,我们观察到没有一个全极化的基态的签名冻结密度。

英文摘要:

We study a two-component mixture of fermionic dipoles in two dimensions at zero temperature, interacting via a purely repulsive $1/r^3$ potential. This model can be realized with ultracold atoms or molecules, when their dipole moments are aligned in the confinement direction orthogonal to the plane. We characterize the unpolarized mixture by means of the Diffusion Monte Carlo technique. Computing the equation of state, we identify the regime of validity for a mean-field theory based on a low-density expansion and compare our results with the hard-disk model of repulsive fermions. At high density, we address the possibility of itinerant ferromagnetism, namely whether the ground state can be fully polarized in the fluid phase. Within the fixed-node approximation, we show that the accuracy of Jastrow-Slater trial wave functions, even with the typical two-body backflow correction, is not sufficient to resolve the relevant energy differences. By making use of the iterative-backflow improved trial wave functions, we observe no signature of a fully-polarized ground state up to the freezing density.

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