Topological phase transition induced by the magnetic proximity effect

The discovery of magnetic topological materials such as magnetic Weyl semimetals (MWSMs) represents an important milestone in spintronics. MWSMs attract significant attention, and there is a demand for experimental evidence of the Weyl phase. The experimental reports are either looking for naturally occurring MWSM candidates or breaking the symmetries of topological phases like a Dirac semimetal. Another route to engineer MWSMs by inducing band inversion through Zeeman splitting from trivial states was theoretically proposed [1], but there has been no experimental report. In this work, we show the evidence for topological phase transitions induced by the magnetic proximity effect. We investigate the topological band structure in bilayers consisting of 1 monolayer-FeAs/α-Sn thin film, using quantum transport measurements and first-principles calculations. The Shubnikov-de Haas oscillations show that there is a linear band with high mobility in our bilayers. Furthermore, first-principles calculation reveals that band inversion occurs in this structure, suggesting that the observed linear band is a surface state within this inversion gap. Our work paves a new way for the realization of magnetic topological materials.

[1] D. Kurebayashi et al., J. Phys. Soc. Jpn. 83, 063709 (2014).