Ultrathin conductive films have a wide range of application prospects in transparent display, flexible electronics, photovoltaics, etc. The industrial applications require the ultrathin layers to possess excellent mechanical properties, exceptionally in thermal stability and corrosion resistance, so that they can be used as the alternative material for the next-generation mobile intelligent devices. Transition metal nitrides like the chromium nitride (CrN) is one of the ideal materials to integrate these excellent properties.
CrN is an excellent prototype material combined high conductivity with a unique antiferromagnetic (AF) configuration. The natural fully compensated magnetic moment in CrN makes it absent of parasitic stray fields and robust against the magnetic perturbations, making it ideal for the secure data storage and memory devices. What’s more, CrN is cost-effective and stable, which is crucial in industrial applications. However, it is a big challenge to fabricate high crystalline quality and homogenous chemical composition of single crystal CrN monocrystals and films.
In this study scientists observed an electronic state transition in highly crystalline antiferromagnetic CrN films with strain and reduced dimensionality. The sample experiment was conducted on the CSNS Multi-purpose Reflectometer, adapting the Polarized Neutron Reflectivity Measurement. The electrical conductivity is observed surprisingly when the CrN layer is as thin as a single unit cell thick, which is far below the critical thickness of most metallic films. This lays a foundation for the application of CrN in making transparent conductive electrode.
Both first-principles calculations and linear dichroism measurements reveal that the strain-mediated orbital splitting effectively customizes the relatively small bandgap at the Fermi level, leading to an exotic phase transition in CrN. The ability to achieve highly conductive nitride ultrathin films by harnessing strain-control over competing phases can be used for utilizing their exceptional characteristics.
Furthermore, within this work, the creation of highly conductive freestanding transition metal nitrides membranes strengthens the great opportunity to combine these technically important materials with other low‐dimensional materials towards functional spintronic devices, flexible electronics, and CMOS techniques in future.
The full publication can be found here https://doi.org/10.1002/adma.202005920
