Altermagnetism induced surface Chern insulator

We introduce a new route to the quantized anomalous Hall effect (QAHE) by coupling an altermagnet to a topological crystalline insulator (TCI). Using first-principles calculations, we show that an altermagnetic RuO2 layer gaps the Dirac surface states of a SnTe TCI slab, opening a 7 meV mass gap on the (110) surface and producing a finite anomalous Hall effect. This mechanism realizes the QAHE in a platform with nearly zero net magnetization, providing robustness and electrical tunability absent in conventional ferromagnetic systems. The concept extends to other altermagnet-TCI combinations, establishing a general family of topological altermagnetic heterostructures that host nontrivial Chern numbers and offer promising opportunities for low-dissipation spintronic devices.