The Zeeman effect, induced by the magnetic field, which can break the Dirac edge states of first-order topological insulators to generate a nontrivial gap, is a physical mechanism for the realization of two-dimensional second-order topological insulators (SOTIs). However, such magnetic-field-driven SOTIs have not yet been experimentally affirmed, and candidate systems in naturally available materials remain scarce. Herein, combining first-principles calculations and effective model analysis, we propose a design strategy to achieve the SOTIs in van der Waals heterobilayers by utilizing the interlayer couplings and out-of-plane magnetic fields. This is different from the previous in-plane magnetic field mechanism. Moreover, we have uncovered that two distinct types of heterobilayers can exhibit the nature of SOTIs, characterized by the shifted Dirac cone, gapped edge states, real-space zero-dimensional corner states, and topological invariants. Our findings not only expand the design avenues of magnetic SOTIs from in-plane to out-of-plane cases but also establish a practical materials framework for the experimental detection of the SOTI phase.

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• Electronic structure
• Symmetry protected topological states
• Topological phase transition
• 2-dimensional systems
• Layered crystals
• Topological materials
• Density functional theory
• High-throughput calculations
• k dot p method