Ferromagnetic behavior induced by La-doping in SrCo2As2

Abstract

Recently, stripe antiferromagnetic spin fluctuations have been observed in SrCo₂As₂, which are similar to those found in AFe₂As₂ superconductors. It is interesting to tune the magnetic properties of this compound to induce superconductivity by chemical doping or applied pressure. Here we present careful chemical doping studies on SrCo₂As₂ by doping the element La on the Sr sites. We found that a dramatic alteration of the magnetic behavior (from paramagnetism to ferromagnetism) was induced by the incorporation of traces of La (2.5%). The results show that ferromagnetic order is preferred over A-type AFM or stripe-type AFM order when SrCo₂As₂ is electron-doped. On this basis, in order to regulate its magnetic ground state with the aim of inducing superconductivity, hole-doping may be superior to electron-doping. Furthermore, an unusual magnetic phase diagram between SrCo₂As₂ and LaCo₂As₂ is also presented in this work.