Structural Tuning of Ferromagnetism in a 3D Cuprate Perovskite

Abstract

The perovskite ${\mathrm{SeCuO}}_{3}$ is unusual for possessing (i) a very small $A$-site $({\mathrm{Se}}^{4+})$ radius, (ii) highly distorted Cu-O-Cu bond angles $\left(\ensuremath{\alpha}\right)$, and (iii) a ferromagnetic (FM) ground state. Negative chemical pressure is applied by replacing Se with Te in solid solution, causing a continuous transformation between the FM state and an antiferromagnetic (AFM) state. This is the first FM-AFM transformation to be controlled by a single microscopic parameter, the in-plane $\ensuremath{\alpha}$, allowing a precise determination of the crossover angle $({\ensuremath{\alpha}}_{c}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}127\ifmmode^\circ\else\textdegree\fi{}\ifmmode\pm\else\textpm\fi{}0.5\ifmmode^\circ\else\textdegree\fi{})$ between FM and AFM superexchange.