Ab initio density-functional calculations show that orthorhombic Pca21 hafnia HfO2 mixed with vanadium at low concentration is a ferroelectric and ferromagnetic insulator. The multiorbital degeneracy of singly-occupied V states in the nominally 4+ ionic state is broken by magnetism, reduced symmetry, and local distortion, causing a single one-electron majority state per V atom to be occupied. A gap of order 1 eV thus survives at all V concentrations, and intrinsic polarization is preserved, at the level of two-thirds the hafnia value. Ferromagnetic magnetization is found to increase linearly with V content, with values of 30-40 emu/cm3 at concentrations near the end of the stability range.
Cite
@article{arxiv.2507.03653,
title = {Vanadium-doped HfO$_2$, multiferroic uncompromised},
author = {Vincenzo Fiorentini and Paola Alippi and Gianaurelio Cuniberti},
journal= {arXiv preprint arXiv:2507.03653},
year = {2025}
}