Electron tunnelling in solids, a fundamental quantum phenomenon, lays the foundation for various modern technologies. The emergence of van der Waals magnets presents opportunities for discovering unconventional tunnelling phenomena. Here, we demonstrate quantum tunnelling with tunable spin geometric phases in a multilayer van der Waals antiferromagnet CrPS₄. The spin geometric phase of electron tunnelling is controlled by magnetic-field-dependent metamagnetic phase transitions. The square lattice of a CrPS₄ monolayer causes strong t_2g-orbital delocalization near the conduction band minimum. This creates a one-dimensional spin system with reversed energy ordering between the t_2g and e_g spin channels, which prohibits both intralayer spin relaxation by means of collective magnon excitations and interlayer spin hopping between the t_2g and e_g spin channels. The resulting coherent electron transmission shows pronounced tunnel magnetoresistance oscillations, manifesting quantum interference of cyclic quantum evolutions of individual electron Bloch waves by means of the time-reversal symmetrical tunnelling loops. Our results suggest the appearance of Aharonov–Anandan phases that originate from the non-adiabatic generalization of the Berry’s phase.

固体中的电子隧穿是一种基本的量子现象，为各种现代技术奠定了基础。范德华磁体的出现为发现非常规的隧道掘进现象提供了机会。在这里，我们展示了多层范德华反铁磁体 CrPS₄ 中具有可调自旋几何相位的量子隧穿。电子隧穿的自旋几何相位由磁场依赖性的超磁相变控制。CrPS₄ 单层的方格在导带最小值附近引起强烈的 t_2g 轨道离域。这创建了一个一维自旋系统，在 t_2g 和 e_g 自旋通道之间具有相反的能量顺序，从而禁止通过集体磁振子激发的层内自旋弛豫以及 t_2g 和 e_g 自旋通道之间的层间自旋跳跃。由此产生的相干电子传输显示出明显的隧道磁阻振荡，通过时间反转对称隧道环表现出单个电子 Bloch 波的循环量子演化的量子干涉。我们的结果表明，Aharonov-Anandan 相的出现起源于 Berry 相的非绝热泛化。