Synthesis and Structural and Magnetic Characterization of Mixed Manganese−Copper n = 1 Ruddlesden−Popper Phases

New n = 1 Ruddlesden−Popper phases containing manganese and copper have been synthesized. Their structure has been investigated by X-ray and neutron powder diffraction and found to be tetragonal ( I 4/ mmm ) at temperatures down to 10 K. The series of materials La x Sr 2- x Mn 0.5 Cu 0.5 O 4 ( x = 0.75, 1, 1.25, 1.5) displays significant Jahn−Teller distortions of the B site cations, with the degree of distortion increasing with x . The materials LaSrMn 0.5 Cu 0.5 O 4, PrSrMn 0.5 Cu 0.5 O 4, and NdSrMn 0.5 Cu 0.5 O 4 show interesting magnetic behavior with antiferromagnetic ordering, but evidence of some ferromagnetic interactions. LaSrMn 0.5 Cu 0.5 O 4 has long-range antiferromagnetic ordering and La 1.5 Sr 0.5 Mn 0.5 Cu 0.5 O 4 shows more complex behavior due to competing interactions, possibly resulting in a canted magnetic ground state.