Spin reorientation of the Fe moments in Eu0.5Ca0.5Fe2As2 : Evidence for strong interplay of Eu and Fe magnetism

Abstract

Using complementary polarized and unpolarized single-crystal neutron diffraction, we have investigated the temperature-dependent magnetic structures of Eu0.5Ca0.5Fe2As2. Upon 50 % dilution of the Eu sites with isovalent Ca 2+ , the Eu sublattice is found to be still long-range ordered below TEu = 10 K, in the A-typed antiferromagnetic (AFM) structure. The moment size of Eu 2+ spins is estimated to be as large as 6.74(4) µB at 2.5 K. The Fe sublattice undergoes a spin-density-wave transition at TSDW = 192(2) K and displays an inplane AFM structure above TEu . However, at 2.5 K, the Fe 2+ moments are found to be ordered in a canted AFM structure with a canting angle of 14(4)°out of the ab plane. The spin reorientation of Fe below the AFM ordering temperature of Eu provides a direct evidence of a strong interplay between the two magnetic sublattices in Eu0.5Ca0.5Fe2As2. PACS numbers:

Microwave analysis of the interplay between magnetism and superconductivity in EuFe2(As1−xPx)2Ghigo1, Torsello2, Gozzelino3 et al. 2019Phys. Rev. Research241290View full textAdd to dashboardCite

“…In the EuFe 2 (As 1−x P x ) 2 compound, it was found that with increasing P substitution, the magnetic moments of the Eu 2+ ions cant out of the ab plane, yielding a net ferromagnetic component along the c direction. Moreover, a possible interplay between Eu and Fe magnetic sublattices should be considered, since the spin reorientation of Fe below the AFM ordering temperature of Eu was recently found in Eu 0.5 Ca 0.5 Fe 2 As 2 [9].…”

Magnetic structures, spin-flop transition, and coupling of Eu and Mn magnetism in the Dirac semimetal EuMnBi2

“…This thus suggests that the coupling of Eu and Mn magnetism strongly depends on the magnetic structure of the Eu sublattice in this system. Given that the magnetic structure of the Eu sublattice can be tuned by an applied field, this may bring new possibilities to continuously tune the interaction between rare-earth-metal and transition-metal magnetic ions by an external magnetic field instead of chemical doping [73,74]. It is also worthwhile to study the Eu-Mn coupling in the future with various field directions.…”

Magnetic structures, spin-flop transition and coupling of Eu and Mn magnetism in the Dirac semimetal EuMnBi$_2$

“…This thus suggests that the coupling of Eu and Mn magnetism strongly depends on the magnetic structure of the Eu sublattice in this system. Given that, the magnetic structure of the Eu sublattice can be tuned by an applied field, this may bring new possibilities to continuously tune the interaction between rare-earth and transition metal magnetic ions by an external magnetic field instead of chemical doping [50,51]. So it is also worth to study the Eu-Mn coupling in the future with various field directions.…”