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arXiv 1306.3124cond-mat.str-elcond-mat.quant-gasquant-ph
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从反铁磁序到二维Fermi哈伯德模型的磁织构

From antiferromagnetic order to magnetic textures in the two dimensional Fermi Hubbard model with synthetic spin orbit interaction

Jiří Minář, Benoît Grémaud

摘要:

本文研究了具有自旋轨道Rashba型合成规范耦合的二维相互作用Fermi-哈伯德模型。利用实空间平均场论,我们数值地确定了不同规范场参数值下相位随相互作用强度的变化。当规范场为固定值时,我们观察到当排斥相互作用的强度增加时,系统进入反铁磁相,然后经历一级相变到非共线磁相。随着规范场参数的变化,该相进一步演化到在大相互作用强度极限下由有效海森堡模型预测的相。我们解释的反铁磁相的存在下,在小的相互作用,从自旋-自旋磁化率的计算显示在低温下的反铁磁有序的发散。我们讨论,如何发散相关的基本费米表面的性质。最后,不同规范场参数的一级相变发生在不相关的临界相互作用强度的事实来自于Hofstadter的情况,即对于不同的磁相位,平均场哈密顿量具有不同的平移对称性。

英文摘要:

We study the interacting Fermi-Hubbard model in two spatial dimensions with synthetic gauge coupling of the spin orbit Rashba type, at half-filling. Using real space mean field theory, we numerically determine the phase as a function of the interaction strength for different values of the gauge field parameters. For a fixed value of the gauge field, we observe that when the strength of the repulsive interaction is increased, the system enters into an antiferromagnetic phase, then undergoes a first order phase transition to an non collinear magnetic phase. Depending on the gauge field parameter, this phase further evolves to the one predicted from the effective Heisenberg model obtained in the limit of large interaction strength. We explain the presence of the antiferromagnetic phase at small interaction from the computation of the spin-spin susceptibility which displays a divergence at low temperatures for the antiferromagnetic ordering. We discuss, how the divergence is related to the nature of the underlying Fermi surfaces. Finally, the fact that the first order phase transitions for different gauge field parameters occur at unrelated critical interaction strengths arises from a Hofstadter-like situation, i.e. for different magnetic phases, the mean-field Hamiltonians have different translational symmetries.

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