发表机构
Department of Physics, University of Dhaka（达卡大学物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究报道了金属交替磁体XCoB$_2$（X=Ta, Zr, Hf），通过交换驱动实现手性磁振子与Weyl态共存，其中Zr和Hf化合物居里温度高于室温，并具有显著反常霍尔效应。
AI 中文摘要
金属交替磁体仍然罕见，尤其是在低对称性三维晶体中，自旋分裂电子带和手性磁振子激发可以共存。我们报道了正交三元硼化物XCoB$_2$（X=Ta, Zr, Hf）中的一族金属$d_{yz}$波交替磁体，它们结晶在中心对称的$Pnma$结构中，具有G型共线磁序。磁性空间群$Pnm'a'$（BNS No.~62.447）内的对称性分析预测了与$k_yk_z$成比例的非相对论自旋分裂，并在$k_y$和$k_z$节面上具有对称性强制的简并，这与第一性原理计算一致。在$k_x=0$平面上，TaCoB$_2$、ZrCoB$_2$和HfCoB$_2$在费米能级处的动量平均自旋分裂分别达到88.4、52.3和70.6 meV，三种化合物中的最大值均超过200 meV。交换分析表明，交替磁磁振子分裂源于对称性不等价的第六近邻子晶格间相互作用。在TaCoB$_2$、ZrCoB$_2$和HfCoB$_2$中，手性分裂在50 meV以下分别达到1.51、2.03和3.10 meV，使其可通过非弹性中子散射探测。蒙特卡洛模拟得到Néel温度分别为$67\pm1.1$、$330\pm5.7$和$307\pm5.0$ K，使ZrCoB$_2$和HfCoB$_2$高于室温。在包含自旋轨道耦合的情况下，三种化合物在费米能级附近都拥有对称性保护的Weyl点、费米弧表面态以及可观的固有反常霍尔电导率$\sigma_{zx}$，在费米能级处分别为$+342$、$-392$和$-221$ S/cm，对于TaCoB$_2$、ZrCoB$_2$和HfCoB$_2$，最大幅度分别达到763、942和924 S/cm。因此，$X$CoB$_2$提供了一个单一补偿平台，同时承载磁振子和电子手性，一个在自旋波中，另一个在贝里曲率中，且没有任何杂散场。
英文摘要
Metallic altermagnets remain rare, particularly in low-symmetry three-dimensional crystals where spin-split electronic bands and chiral magnon excitations can coexist. We report a family of metallic $d_{yz}$-wave altermagnets in the orthorhombic ternary borides XCoB$_2$ (X = Ta, Zr, Hf), which crystallize in the centrosymmetric $Pnma$ structure with G-type collinear magnetic order. Symmetry analysis within the magnetic space group $Pnm'a'$ (BNS No.~62.447) predicts a nonrelativistic spin splitting proportional to $k_yk_z$, with symmetry-enforced degeneracy on the $k_y$ and $k_z$ nodal planes, consistent with first-principles calculations. On the $k_x=0$ plane, the momentum-averaged spin splitting reaches 88.4, 52.3, and 70.6~meV at the Fermi level in TaCoB$_2$, ZrCoB$_2$, and HfCoB$_2$, respectively, with maxima exceeding 200~meV in all three compounds. Exchange analysis shows that the altermagnetic magnon splitting originates from symmetry-inequivalent sixth-neighbour inter-sublattice interactions. The chirality splitting reaches 1.51, 2.03, and 3.10 meV below 50 meV in TaCoB$_2$, ZrCoB$_2$, and HfCoB$_2$, respectively, making it accessible to inelastic neutron scattering. Monte Carlo simulations yield N'eel temperatures of $67\pm1.1$, $330\pm5.7$, and $307\pm5.0$~K, placing ZrCoB$_2$ and HfCoB$*2$ above room temperature. With spin-orbit coupling included, all three compounds host symmetry-protected Weyl points near the Fermi level, Fermi-arc surface states and sizable intrinsic anomalous Hall conductivities $σ*{zx}$ of $+342$, $-392$, and $-221$~S/cm at the Fermi level, reaching maximum magnitudes of $763$, $942$, and $924$~S/cm for TaCoB$_2$, ZrCoB$_2$, and HfCoB$_2$, respectively. $X$CoB$_2$ therefore provides a single compensated platform carrying both magnonic and electronic chirality, one in the spin waves and the other in the Berry curvature, without any stray field.
