Visualization of the magnetic flux structure in phosphorus-doped EuFe2As2 single crystals

Abstract

Magnetic flux structure on the surface of EuFe2(As1−xPx)2 single crystals with nearly optimal phosphorus doping levels x = 0.20, and x = 0.21 is studied by low-temperature magnetic force microscopy and decoration with ferromagnetic nanoparticles. The studies are performed in a broad temperature range. It is shown that the single crystal with x = 0.21 in the temperature range between the critical temperatures TSC = 22 K and TC = 17.7 K of the superconducting and ferromagnetic phase transitions, respectively has the vortex structure of a frozen magnetic flux, typical for type-II superconductors. The magnetic domain structure is observed in the superconducting state below TC. The nature of this structure is discussed.

Microwave analysis of the interplay between magnetism and superconductivity in EuFe2(As1−xPx)2Ghigo1, Torsello2, Gozzelino3 et al. 2019Phys. Rev. ResearchSelf Cite241290View full textAdd to dashboardCite

“…9(a)] and to ab planes [ Fig. 9(b)] for a EuFe 2 (As 1−x P x ) 2 crystal with x = 0.20, measured by a SQUID magnetometer [38]. An evident feature is shown at about 18 K, where the susceptibility first increases upon cooling and then shows a peak, unlike in nonmagnetic superconductors.…”

RbEu(Fe1−xNix)4As4 : From a ferromagnetic superconductor to a superconducting ferromagnet

“…The expected fine ferromagnetic domains that are antiferromagnetically aligned could give rise to a PLA in the FC M (T ) curve. Future studies with singlecrystalline samples by magnetic-force microscopy [42] seem promising to clarify this issue. Table I).…”

High-Frequency ac Susceptibility of Iron-Based Superconductors

“…IBS compounds containing magnetic rare-earth elements, such as the EuFe As -based systems, in addition possess local magnetic moments that can result in further magnetic ordering. In fact, when superconductivity is induced by chemical pressure through the isovalent substitution of P in the site of As (EuFe (As P ) ), the magnetic moments of the Eu ions, initially in AFM order, cant out of the plane, yielding a net ferromagnetic component along the c direction [ 54 ] that, coexisting with superconductivity [ 55 ], induces a rich spontaneous vortex physics [ 56 , 57 , 58 ]. The onset of this ferromagnetic order at the temperature , and typical transitions due to its dynamics, at temperatures and , can be recognized clearly in the features shown in Figure 7 a [ 33 , 59 ].…”