This is a preliminary report on square hysteresis loops obtained on polycrystalline yttrium iron garnets that have Tb3+or Eu3+partially replacing the Y3+ions. Reasonably square hysteresis loops that are technologically important can be produced. In addition, a cobalt‐containing‐garnet responds to a magnetic annealing treatment and has substantial values of uniaxial anisotropy at room temperature. This work indicates a method of producing other garnets which will respond to the magnetic annealing process.