The spinel $\mathrm{CoC}{\mathrm{r}}_2{\mathrm{O}}_4$ (CCO) is one of the few bulk multiferroics with net magnetic moment. However, studies on the properties of CCO thin films are scarce. Here, we investigate the interplay between microstructure and magnetism of a series of CCO epitaxial thin films by means of x-ray diffraction, magnetometry, and aberration-corrected scanning transmission electron microscopy (STEM). Optimum pristine CCO films can be grown on a substrate with spinel structure $\left(\mathrm{MgA}{\mathrm{l}}_2{\mathrm{O}}_4\right)$, despite the large lattice mismatch of $\sim 3\%$. On the contrary, a substrate with lower lattice mismatch $(\sim 1\%)$ but with the rock salt structure (MgO) favors the degradation of the CCO crystal quality by forming antiphase boundaries (APBs), drastically weakening the magnetization, in agreement with reports for other spinel films. Nevertheless, our results also show that the type and number of APBs can be tuned by changing the growth temperature to favor the ferromagnetic alignment between antiphase domains, giving rise to a partial recovery of the magnetization.

• Received 12 April 2017
• Revised 30 June 2017

DOI:https://doi.org/10.1103/PhysRevB.96.104105