Theoretical Study Revealing Possibility of A Quantum Material To Transport Zero-Resistance Current Above Room Temperature

Topological insulator is a new quantum state realized by spin-orbit coupling. Its exploration has been the new frontier of condensed matter physics and material sciences recently. In a topological insulator, while insulating in the bulk, a sample possesses a quantum edge state which can transport dissipationless current, distinguishing itself from conventional insulators. Novel nano quantum functions of this new class of materials are explored. Unfortunately, it was realized only at very low temperature so far, and in the edge state spin-up and spin-down electrons are mixed, limiting its application.

Based on symmetry analysis and first-principles calculations, this group has discovered that one can achieve a new state called antiferromagnetic topological insulator by inserting a [111] mono-atomic layer of gold (Au) into a Mott insulator LaCrO3 of perovskite structure and applying an electric field along [111] direction. This theoretical work reveals a new direction for exploring topological materials and novel quantum functions.

The paper summarizing the new theory has been published in an open-access journal (Q. –F. Liang, L. –H. Wu and X. Hu, New Journal of Physics, vol.15, 063031, 2013). Patent has also been applied (12-MS-111SE).