arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2103.13038cond-mat.str-el
收藏

磁性I型和II型Weyl半金属的自旋磁化率

Spin susceptibilities in magnetic type-I and type-II Weyl semimetals

Feng Xiong, Xingjie Han, Carsten Honerkamp

摘要:

本文研究了$\mathcal{T}$ -反转对称破缺Weyl半金属晶格模型中的相互作用自旋极化率。我们采用了随机相位近似(RPA)方法的自旋SU(2)-破缺的情况下,包括混合的阶梯图和气泡图,超越了SU(2)-对称的情况。在这种方法中,磁有序的趋势和能带结构倾斜参数$γ$在不同温度下的关系进行了探讨。当倾斜项从I型Weyl半金属变为II型时,磁有序的临界相互作用强度$U_c$减小。温度越低,在它们之间的临界点处的$U_c$的下降越急剧。还研究了半填充附近的轻微掺杂的$U_c$的变化。结果表明,这些Weyl系统具有强各向异性的自旋响应,在垂直于倾斜方向上具有增强的双简并横向磁化率,这是从裸哈密顿量的$\mathcal{C}_{4z}$有理对称性继承来的,但纵向响应相对于该对称性受到抑制.对于小倾角$γ$和足够强的相互作用,我们发现了两种简并有序模式,其自旋序与倾角方向正交,但自旋相关长度与自旋方向平行。随着倾斜度的增加,系统发展不稳定性相对于平面内磁序与波矢量$(0,π, q_z)$和$(π,0, q_z)$,与$q_z$从0增加到$π$过渡到II型Weyl半金属之前达到。这些结果表明,更丰富的相关Weyl半金属的磁相,也提出了精确的理论描述的挑战。

英文摘要:

We investigate interacting spin susceptibilities in lattice models for $\mathcal{T}$-reversal symmetry-broken Weyl semimetals. We employ a random phase approximation (RPA) method for the spin-SU(2)-symmetry-broken case that includes mixtures of ladder and bubble diagrams, beyond a SU(2)-symmetric case. Within this approach, the relations between the tendency towards magnetic order and the band structure tilt parameter $γ$ under different temperatures are explored. The critical interaction strength $U_c$ for magnetic ordering decreases as the tilt term changes from type-I Weyl semimetals to type-II. The lower temperature, the sharper is the drop in $U_c$ at the critical point between them. The variation of $U_c$ with a slight doping near half-filling is also studied. It is generally found that these Weyl systems show a strongly anisotropic spin response with an enhanced doubly degenerate transverse susceptibility perpendicular to tilt direction, inherited from $\mathcal{C}_{4z}$ rational symmetry of bare Hamiltonian, but with the longitudinal response suppressed with respect to that. For small tilts $γ$ and strong enough interaction, we find two degenerate ordering patterns with spin order orthogonal to the tilt direction but much shorter spin correlation length parallel to the spin direction. With increasing the tilt, the system develops instabilities with respect to in-plane magnetic orders with wavevector $(0,π, q_z)$ and $(π,0, q_z)$, with $q_z$ increasing from 0 to $π$ before the transition to a type-II Weyl semimetal is reached. These results indicate a greater richness of magnetic phases in correlated Weyl semimetals that also pose challenges for precise theoretical descriptions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑