Based on first-principles calculations, we predict that $5d$ transition metals on graphene present a unique class of hybrid systems exhibiting topological transport effects that can be manipulated effectively by external electric fields. The origin of this phenomenon lies in the exceptional magnetic properties and the large spin-orbit interaction of the $5d$ metals leading to significant magnetic moments accompanied with colossal magnetocrystalline anisotropy energies. A strong magnetoelectric response is predicted that offers the possibility to switch the spontaneous magnetization direction by moderate electric fields, enabling an electrically tunable quantum anomalous Hall effect.

Electrically Tunable Quantum Anomalous Hall Effect in Graphene Decorated by<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>5</mml:mn><mml:mi>d</mml:mi></mml:math>Transition-Metal Adatoms

Electrically Tunable Quantum Anomalous Hall Effect in Graphene Decorated by5dTransition-Metal Adatoms