Polar Behavior in a Magnetic Perovskite Via A-Site Disorder

We elucidate a mechanism for obtaining polar behavior in magnetic perovskites based on A-site disorder and demonstrate this mechanism by density functional calculations for the double perovskite (La,Lu)MnNiO$_6$ with Lu concentrations at and below 50%. We show that this material combines polar behavior and ferromagnetism. The mechanism is quite general and may be applicable to a wide range of magnetic perovskites.