Lorentz-violating type-II nodal lines exhibit attracting physical properties and have been hot discussed currently. However, their investigations have been mostly limited in nonmagnetic system because of lacking ideal spin-polarized candidates with clean type-II nodal line states. Here, for the first time, we report the family of X₂YZ₄ (X = K, Cs, Rb, YCr, Cu, Z = Cl, F) compounds are such ideal candidate materials by using the member of K₂CuF₄ as an example. We show the material is a ferromagnetic half-metal with weak anisotropy, which host fully spin-polarized conducting electrons. In the conducting spin channel, the band crossing form a pair of type-II nodal lines, protected by mirror symmetry. These type-II nodal lines are different with former proposed examples because they have a 100% spin polarization. In addition, we also show the material can realize switchable topological states, which can be easily controlled by external magnetic field. It is noticed that, the material: i) is stable and can be synthesized in experiments; ii) has clear magnetic structure; and iii) manifests clean type-II nodal line state and clear drumhead surface states. Therefore, the proposed X₂YZ₄ compounds are expected to be an excellent platform to investigate the novel physical properties of both type-II nodal line states with complete spin polarization.

违反洛伦兹的II型结线表现出吸引人的物理特性，目前已受到热议。但是，由于缺乏具有干净的II型节点线状态的理想自旋极化候选物，他们的研究大多局限于非磁性系统。在这里，我们首次报道了通过使用K ₂ CuF的成员，X ₂ YZ _4族（X = K，Cs，Rb，Y Cr，Cu，Z = Cl，F）是这种理想的候选材料。₄举个例子。我们显示该材料是各向异性弱的铁磁半金属，其具有完全自旋极化的导电电子。在导电自旋通道中，带交叉形成一对II型节点线，并受到镜像对称性的保护。这些II型节点线与以前提出的示例不同，因为它们具有100％的自旋极化。此外，我们还显示了该材料可以实现可切换的拓扑状态，可以轻松地通过外部磁场对其进行控制。注意到，材料：i）是稳定的并且可以在实验中合成；ii）具有清晰的磁性结构；iii）表现出清洁的II型结线状态和清晰的鼓面表面状态。因此，建议X ₂ YZ ₄ 这些化合物有望成为研究具有完全自旋极化的两种II型结线态的新物理性质的绝佳平台。