# Novel Chern insulators with half-metallic edge states

## TL;DR

This paper predicts that Cu2S/MnSe heterostructures can act as Chern insulators with fully spin-polarized, high-velocity edge states, offering a new pathway for designing efficient spintronic devices.

## Contribution

It introduces a novel mechanism for creating Chern insulators with half-metallic edge states in heterostructures with normal band order, expanding material options for spintronics.

## Key findings

- Cu2S/MnSe heterostructures exhibit topological Chern insulating states.
- Edge states are fully spin-polarized and robust against chemical potential tuning.
- High Fermi velocity of 0.87 million m/s in edge states.

## Abstract

The central target of spintronics research is to achieve flexible control of highly efficient and spin-polarized electronic currents. Based on first-principles calculations and k-p models, we demonstrate that Cu2S/MnSe heterostructures are a novel type of Chern insulators with half-metallic chiral edge states and a very high Fermi velocity (0.87 * 10^6 m/s). The full spin-polarization of the edge states is found to be robust against the tuning of the chemical potential. Unlike the mechanisms reported previously, this heterostructure has quadratic bands with a normal band order, that is, the p/d-like band is below the s-like band. Charge transfer between the Cu2S moiety and the substrate results in variation in the occupied bands, which together with spin-orbit coupling, triggers the appearance of the topological state in the system. These results imply that numerous ordinary semiconductors with normal band order may convert into Chern insulators with half-metallic chiral edge states through this mechanism, providing a strategy to find a rich variety of materials for dissipationless, 100% spin-polarized and high-speed spintronic devices.

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Source: https://tomesphere.com/paper/1901.00629