Janus monolayer TaNF: a new ferrovalley material with large valley splitting and tunable magnetic properties

TL;DR

This paper predicts a new Janus TaNF monolayer with large valley splitting, tunable magnetic properties, and high Curie temperature, making it promising for valleytronics and spintronics applications.

Contribution

The study introduces a novel Janus TaNF monolayer with unique ferroelectric, magnetic, and valleytronic properties, demonstrated through first-principles calculations.

Findings

Exhibits large intrinsic valley splitting due to spin polarization and SOC.

High Curie temperature of 373 K under -3% biaxial strain.

Band gap can be tuned from semiconductor to semi-metal by strain.

Abstract

Materials with large intrinsic valley splitting and high Curie temperature are a huge advantage for studying valleytronics and practical applications. In this work, using first-principles calculations, a new Janus TaNF monolayer is predicted to exhibit excellent piezoelectric properties and intrinsic valley splitting, resulting from the spontaneous spin polarization, the spatial inversion symmetry breaking and strong spin-orbit coupling (SOC). TaNF is also a potential two-dimensional (2D) magnetic material due to its high Curie temperature and huge magnetic anisotropy energy. The effective control of the band gap of TaNF can be achieved by biaxial strain, which can transform TaNF monolayer from semiconductor to semi-metal. The magnitude of valley splitting at the CBM can be effectively tuned by biaxial strain due to the changes of orbital composition at the valleys. The magnetic anisotropy energy (MAE) can be manipulated by changing the energy and occupation (unoccupation) states of d orbital compositions through biaxial strain. In addition, Curie temperature reaches 373 K under only -3% biaxial strain, indicating that Janus TaNF monolayer can be used at high temperatures for spintronic and valleytronic devices.