Magnetic structure of theEu2+moments in superconductingEuFe2(As1−xPx)2withx=0.19

Abstract

The magnetic structure of the ${\mathrm{Eu}}^{2+}$ moments in the superconducting ${\mathrm{EuFe}}_{2}{({\mathrm{As}}_{1\ensuremath{-}x}{\mathrm{P}}_{x})}_{2}$ sample with $x=0.19$ has been determined using neutron scattering. We conclude that the ${\mathrm{Eu}}^{2+}$ moments are aligned along the c direction below ${T}_{\mathrm{C}}=19.0(1)$ K with an ordered moment of 6.6(2) ${\ensuremath{\mu}}_{B}$ in the superconducting state. An impurity phase similar to the underdoped phase exists within the bulk sample which orders antiferromagnetically below ${T}_{\mathrm{N}}=17.0(2)$ K. We found no indication of iron magnetic order, nor any incommensurate magnetic order of the ${\mathrm{Eu}}^{2+}$ moments in the sample.