(La sub(1-x) Ba sub(x))(Zn sub(1-x) Mn sub(x))AsO: A two-dimensional 1111-type diluted magnetic semiconductor in bulk form

We report the synthesis and characterization of a bulk diluted magnetic semiconductor (La sub(1-x) Ba sub(x)) (Zn sub(1-x)Mn sub(x))AsO (0 [< or =, slant] x [< or =, slant] 0.2) with a layered crystal structure identical to that of the 1111-type FeAs superconductors. No ferromagnetic order occurs with (Zn,Mn) substitution in the parent compound LaZnAsO without charge doping. Together with carrier doping via (La.Ba) substitution, a small amount of Mn substituting for Zn results in ferromagnetic order with T sub(C) up to ~40 K, although the system remains semiconducting. Muon spin relaxation measurements confirm the development of ferromagnetic order in the entire volume, with the relationship between the internal field and T sub(C) consistent with the trend found in (Ga,Mn)As and the 111-type Li(Zn,Mn)As and the 122-type (Ba,K) (Zn,Mn) sub(2)As sub(2) systems.