论文标题

凝结物质Weyl Systems中的扭转Landau水平和几何异常

Torsional Landau levels and geometric anomalies in condensed matter Weyl systems

论文作者

Laurila, Sara, Nissinen, Jaakko

论文摘要

我们考虑坐标依赖性四元(“ Fermi速度”),动量空间几何形状和扭转Landau水平(LLS)在具有低能量Weyl Quasiparticles的浓缩物质系统中的作用。与它们的相对论对应物相反,它们是在有限的动量中出现的,并且对线性光谱的明确截止。通过四四型与动量的通用耦合,它们具有重力特征的几何性手性和轴向异常。更确切地说,在低能量的情况下,费米子经历了与新兴各向异性的Riemann-Cartan和Newton-Cartan Pastectimes相对应的背景字段,这取决于低能分散体的形式。在这些背景下,我们展示了扭转和Nieh-Yan(NY)异常如何出现在具有动量尺寸的紫外线(UV)参数的冷凝物质Weyl系统中。扭转NY异常以最简单的术语从有限动量的扭转lls的光谱与节点耦合到节点的光谱以及截止线的线性近似。我们仔细回顾了零动量的相对论费米的扭转异常和光谱流,并将其与光谱,非零扭转异常以及在有限动量的凝结物质系统中的尺寸UV-Cutoff参数进行对比。我们将其应用于对弹性菌株下非基质手性超导体,超流体和Weyl半含量的敏感的四个敏感的四元异常。与(伪)仪表场相比,这会导致几何形状的节点处的异常密度抑制。我们还简要讨论了非偏见的Weyl费米子在异常热传输中的作用,该旋转是通过Luttinger的虚拟引力场产生的,该引力场与热梯度相对应。

We consider the role of coordinate dependent tetrads ("Fermi velocities"), momentum space geometry, and torsional Landau levels (LLs) in condensed matter systems with low-energy Weyl quasiparticles. In contrast to their relativistic counterparts, they arise at finite momenta and an explicit cutoff to the linear spectrum. Via the universal coupling of tetrads to momentum, they experience geometric chiral and axial anomalies with gravitational character. More precisely, at low-energy, the fermions experience background fields corresponding to emergent anisotropic Riemann-Cartan and Newton-Cartan spacetimes, depending on the form of the low-energy dispersion. On these backgrounds, we show how torsion and the Nieh-Yan (NY) anomaly appear in condensed matter Weyl systems with a ultraviolet (UV) parameter with dimensions of momentum. The torsional NY anomaly arises in simplest terms from the spectral flow of torsional LLs coupled to the nodes at finite momenta and the linear approximation with a cutoff. We carefully review the torsional anomaly and spectral flow for relativistic fermions at zero momentum and contrast this with the spectral flow, non-zero torsional anomaly and the appearance the dimensionful UV-cutoff parameter in condensed matter systems at finite momentum. We apply this to chiral transport anomalies sensitive to the emergent tetrads in non-homogenous chiral superconductors, superfluids and Weyl semimetals under elastic strain. This leads to the suppression of anomalous density at nodes from geometry, as compared to (pseudo)gauge fields. We also briefly discuss the role torsion in anomalous thermal transport for non-relativistic Weyl fermions, which arises via Luttinger's fictitious gravitational field corresponding to thermal gradients.

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