Fe₃O₄ (magnetite) and ferrites like MgFe₂O₄ and ZnFe₂O₄ are examples of which of the following substances?

Ferrimagnetic substances

Ferrimagnetism: Ferrimagnetism is observed when the magnetic moments of the domains in the substance are aligned in parallel and anti-parallel directions in unequal numbers. They are weakly attracted by magnetic field as compared to ferromagnetic substances. Fe₃O₄ (magnetite) and ferrites like MgFe₂O₄ and ZnFe₂O₄ are examples of such substances. These substances also lose ferrimagnetism on heating and become paramagnetic.