Researchers proposed a new strategy to explore various quantum phases and used it to predict the first room-temperature quantum anomalous Hall effect in a 2D post-transition metal system. The strategy, used to explore strain engineering of magnetic ordering and band topology, may inform the design of promising quantum materials for spintronic and other advanced computational devices
Novel heterostructures promise useful quantum phases, including quantum spin Hall insulators (QSHIs), quantum anomalous Hall insulators (QAHIs), 2D magnetic Weyl semimetals, and 2D ferromagnetic semiconductors. QAHIs exhibit precise quantization and robustness against defects along spin-polarized edges that serve as electron channels. Realization of a high-temperature QAHI effect has been hindered by the difficulty of simultaneously controlling magnetization and spin-orbit coupling (SOC). Here, first-principles calculations combined with an effective Hamiltonian approach demonstrated that substrate strain could change a 2D lattice’s topological and magnetic properties to explore various quantum phases. Notably, the researchers, for the first time, demonstrate a system of nonmagnetic post-transition metals that underwent a first-order phase transition to a ferromagnetic state by strain. They established diagrams of many quantum phases, broadly demonstrating that strained substrates can be used to explore versatile magnetic, electronic, and quantum topological properties.
