Helical spin order in EuFe2As2 and EuRbFe4As4 single crystals

Abstract

In this work, fabrication and characterization of magnetic properties of EuFe 2 As 2 and EuRbFe 4 As 4 single crystals is reported. Magnetization measurements of samples with well defined thin film geometry and crystal orientation demonstrate a striking similarity in ferromagnetic properties of Eu subsystems in these two compounds. Measurements with magnetic field applied along ab crystal planes reveal meta-magnetic transition in both compounds. Numerical studies employing the J z1 and J z2 Heisenberg model suggest that the ground state of the magnetic order in Eu subsystem for both compounds is the helical spin order with the helical angle about 2π/5, while the meta-magnetic transition is the helix-to-fan first order phase transition.

Iron-based magnetic superconductors AEuFe4As4 (A = Rb, Cs): natural superconductor–ferromagnet hybrids

“…The obtained crystals are pure, and are relatively large (2.0 × 2.0 × 0.2 mm 3 ). Recently, Vlasenko and co-workers [77][78][79] and Hemmida et al [80] reported the successful growth of RbEuFe 4 As 4 with FeAs flux. The obtained thin crystals are as large as 5 × 5 mm 2 in the ab plane, although the crystals contain small amount of EuFe 2 As 2 impurities [77][78][79].…”

“…Recently, Vlasenko and co-workers [77][78][79] and Hemmida et al [80] reported the successful growth of RbEuFe 4 As 4 with FeAs flux. The obtained thin crystals are as large as 5 × 5 mm 2 in the ab plane, although the crystals contain small amount of EuFe 2 As 2 impurities [77][78][79]. At present, growth of large high-quality crystals of RbEuFe 4 As 4 , CsEuFe 4 As 4 , and the doped variants is still challenging.…”