Evidence of magnetism-induced topological protection in the axion insulator candidate EuSn <sub>2</sub> P <sub>2</sub>
Gian Marco Pierantozzi, Alessandro De Vita, Chiara Bigi, Xin Gui, Hung‐Ju Tien, Debashis Mondal, Federico Mazzola, Jun Fujii, I. Vobornik, Giovanni Vinai, Alessandro Sala, Cristina Africh, Tien‐Lin Lee, G. Rossi, Tay‐Rong Chang, Weiwei Xie, R. J. Cava, G. Panaccione
Abstract
Significance Understanding the mutual influence between magnetic and topological properties in a solid system is a fundamental challenge for quantum materials research. The so-called axion insulator is one such case, with exotic properties related to the magnetoelectric effect. In this work, by combining chemical and magnetic-state sensitive electron and X-ray spectroscopies with first-principle calculations we reveal that EuSn 2 P 2 holds the characteristics of an axion insulator and displays “hidden” electronic properties arising from its layer-dependent ferromagnetic character. As a function of the termination, we observe specific electronic states, holding a spin arrangement representative of a topological insulator. Furthermore, the direction of magnetization enables topological protection, a key property related to axion-based physics.