论文标题
无质量的多率HOPF半学
Massless multifold Hopf semimetals
论文作者
论文摘要
三维拓扑半学表现出线性能带交叉点，它们充当浆果曲率的单孔。在这里，引入了替代类别的半学等级，其中包含线性$ n $折叠点，每个杂交点是\ emph {berry dipole}的来源。我们为这种\ emph {无质量的多率霍普夫半仪（MMHSS）}构建了连续性和晶格模型，其中$ n = 3,4,5 $频段和研究浆果偶极交叉的非繁琐效果：（i）通过相对磁场轴的磁场轴的磁场量的Landau水平频谱可进行强烈调谐。 （ii）一个异常的霍尔电导率，是费米水平的奇数功能。 （iii）类似于手性异常，手性磁性和磁性磁性效应的弱场耗散磁性磁性，熟悉了一对耦合的Weyl节点，但甚至是费米水平的功能。通过扩大MMHSS，获得了高达$ \ Mathcal {n} _ \ text {hopf} = 10 $的多型霍普夫绝缘子，获得了一个肥沃的操场，以探索精致的拓扑。
Three-dimensional topological semimetals exhibit linear energy band crossing points that act as monopoles of Berry curvature. Here, an alternative class of semimetals is introduced, featuring linear $N$-fold crossing points each of which acts as a source of a \emph{Berry dipole}. We construct continuum and lattice models for such \emph{massless multifold Hopf semimetals (MMHSs)} with $N=3,4,5$ bands and study nontrivial effects of a Berry dipole crossing: (i) A Landau level spectrum that is strongly tunable by the orientation of the magnetic field relative to the dipole axis. (ii) An anomalous Hall conductivity that is an odd function of the Fermi level. (iii) Weak-field dissipative magnetoconductivities that resemble the chiral anomaly, chiral magnetic and magnetochiral effects familiar from a pair of coupled Weyl nodes, but that are even functions of the Fermi level. By gapping out MMHSs, multiband Hopf insulators with Hopf numbers as high as $\mathcal{N}_\text{Hopf}=10$ are obtained, providing a fertile playground to explore delicate topology.
