ES22 Poster Session

Kayahan Saritas, Yale University

Title: Magnetic anisotropy densities through second order perturbation theory

Text: Piezoelectric ferromagnets (PFM) are characterized by having a piezo-active crystalline symmetry and possessing ferromagnetic ordering. Piezoelectrics change their dimensions when exposed to electric field which can lead to a change in the critical temperature of ferromagnetic interactions. Our first-principles calculations with data-mining approach reveal 2H-FeCl$_2$ as the only two-dimensional (2D) monolayered PFM with its critical temperature (Tc) near room temperature at 260K. Mermin-Wagner theorem asserts easy-axis magnetic anisotropy for ferromagnetic order in 2D materials. We explain the origin of easy-axis magnetic anisotropy in FeCl$_2$ quantitatively, by developing magnetic anisotropy {\it densities}. Our methods explain the origin of easy-plane and easy-axis anisotropies in VSe$_2$ and CrI$_3$ respectively. We show that the magnetic anisotropy of FeCl$_2$ can be enhanced up to 6-folds with only fractional hole doping. Our results offer design principles to aid the search for new 2D PFM for novel applications.