Evolution of magnetism in cerium doped LaCo2P2 crystals: a magnetic phase diagram

ThCr2Si2-type phosphide ACo2P2 (A=Rare earth elements) has the same structure as iron arsenides, but their magnetic behaviors are quite distinct. In this paper, we for the first time grew a series of La1-xCexCo2P2 single crystals (x=0.0 to1.0), and made structural and magnetic characterizations. This allows us to carry out a careful investigation on the evolution of magnetism with cerium content and build a magnetic phase diagram. We found that the introduction of cerium induces a rapid decrease of c-axis and a change from ferromagnetic (FM) to antiferromagnetic (AFM) states. By employing first-principles band-structure calculations, we identify the formation of P-P bonding with the shortening of c-axis, which effectively drives an increase of AFM interaction and eventually leads to AFM ordering in the high doping region. The present study may shed light on the interplay between the structural collapsing and electronic/magnetic properties in 122 iron pnictides.