Quantum Monte Carlo Study of Electronic and Structural properties of Hafnia Polymorphs*

We have used Diffusion Monte Carlo (DMC) to study the structural and electronic properties of HfO₂ polymorphs. Hafnia has received a great deal of attention due to its wide range of application in industrial devices, such as optical coating, high-k dielectrics, and resistive random access memory (RRAM). Through X-ray diffraction measurement, three different polymorphs of hafnia were reported at low pressure, however, their electronic and structural properties are still not well understood because standard Density Functional Theory (DFT) approaches do not work well, and there is a scarcity of experimental data. Based on recent success using DMC in providing accurate electronic properties for zirconia polymorphs[1] (electronic structure similar to hafnia), we investigated detailed electronic properties of the cubic, tetragonal, and monoclinic phase of hafnia. In addition to DMC, we benchmarked DFT using various hybrid exchange-correlation functionals and used the best results to go beyond what DMC allows in terms of band structures and projected densities of state.
[1] A. Benali et al., https://arxiv.org/abs/1708.09424