Recent studies have shown that layered compound EuCd₂As₂ could exhibit diverse topological states depending on the different magnetic structures, such as Weyl semimetal, Dirac semimetal and topological insulator. In order to further study the interplay between magnetism and topology of EuCd₂As₂, it is necessary to figure out its magnetic structure. Here, by magnetization (M) measurements and negative magnetostriction (λ) along the [001] direction measured by scanning tunneling microscopy on EuCd₂As₂ single crystals, we observe field-induced metamagnetic phase transition from A-type antiferromagnetic (AFM) ground state to field-polarized state, with canted AFM (CAFM) state in between. Magnetization and magnetostriction are more sensitive to the in-plane field than the out-of-plane field, indicating the magnetic moments lying in the ab plane. The absence of abrupt jump on M-H and λ-H curves demonstrates that the phase transition is a second-order type. In CAFM state, M increases linearly with the field and λ is proportional to M². Tunneling conductance spectra show the field-induced evolution of the electronic density of states. Our results provide experimental evidence for understanding the magnetic structure of EuCd₂As₂.

最近的研究表明，层状化合物EuCd ₂ As ₂可以表现出不同的拓扑状态，这取决于不同的磁性结构，例如外尔半金属、狄拉克半金属和拓扑绝缘体。为了进一步研究EuCd ₂ As ₂的磁性和拓扑结构之间的相互作用，有必要弄清楚它的磁性结构。在这里，通过磁化 ( M ) 测量和沿 [001] 方向的负磁致伸缩 ( λ ) 通过扫描隧道显微镜在 EuCd ₂ As _2上测量单晶，我们观察到场诱导的从 A 型反铁磁 (AFM) 基态到场极化态的超磁相变，其间有倾斜 AFM (CAFM) 态。磁化和磁致伸缩对面内场比面外场更敏感，表明磁矩位于ab平面内。M - H和λ - H曲线上没有突然跳跃表明相变是二阶类型。在 CAFM 状态下，M随场线性增加，λ与M ²成正比. 隧道电导谱显示了电子态密度的场诱导演化。我们的研究结果为理解EuCd ₂ As ₂的磁性结构提供了实验证据。