Van der Waals (vdW) ferromagnets have enabled the development of heterostructures assembled from exfoliated monolayers with spintronics functionalities, making it important to understand and ultimately tune their magnetic properties at the microscopic level. Information about the magnetic properties of these systems comes, so far, largely from macroscopic techniques, with little being known about the microscopic magnetic properties. Here, we combine spin-polarized scanning tunneling microscopy and quasiparticle interference imaging with neutron scattering to establish the magnetic and electronic properties of the metallic vdW ferromagnet ${\mathrm{Fe}}_3{\mathrm{GeTe}}_2$. By imaging domain walls at the atomic scale, we can relate the domain wall width to the exchange interaction and magnetic anisotropy extracted from the magnon dispersion as measured in inelastic neutron scattering, with excellent agreement between the two techniques. From comparison with density functional theory calculations we can assign the quasiparticle interference to be dominated by spin-majority bands. We find a dimensional dichotomy of the bands at the Fermi energy: bands of minority character are predominantly two-dimensional in character, whereas the bands of majority character are three-dimensional. We expect that this will enable new design principles for spintronics devices.

中文翻译：

---

范德华铁磁体 Fe3GeTe2 中的自旋极化 STM 成像和非弹性中子散射的关系

范德华 (vdW) 铁磁体已经能够开发由具有自旋电子学功能的剥离单层组装而成的异质结构，这使得在微观水平上理解并最终调整其磁性非常重要。到目前为止，有关这些系统的磁特性的信息主要来自宏观技术，而对微观磁特性知之甚少。在这里，我们将自旋极化扫描隧道显微镜和准粒子干涉成像与中子散射相结合，以建立金属 vdW 铁磁体的磁性和电子特性${铁}_3{\mathrm{锗碲}}_2$. 通过在原子尺度上成像畴壁，我们可以将畴壁宽度与在非弹性中子散射中测量的从磁振子色散中提取的交换相互作用和磁各向异性联系起来，这两种技术之间具有很好的一致性。通过与密度泛函理论计算的比较，我们可以将准粒子干涉指定为由自旋多数带支配。我们发现费米能带的维度二分法：少数特征的能带主要是二维的，而多数特征的能带是三维的。我们预计这将为自旋电子设备提供新的设计原则。