Long-range magnetic order in hydroxide-layer-doped (Li1−x−yFexMnyOD)FeSe

Abstract

The (Li1−xFexOH)FeSe superconductor has been suspected to exhibit long-range magnetic ordering due to Fe substitution in the LiOH layer. However, no direct observation such as magnetic reflection from neutron diffraction has be reported. Here, we use a chemical design strategy to manipulate the doping level of transition metals in the LiOH layer to tune the magnetic properties of the (Li1−x−yFexMnyOD)FeSe system. We find Mn doping exclusively replaces Li in the hydroxide layer resulting in enhanced magnetization in the (Li0.876Fe0.062Mn0.062OD)FeSe superconductor without significantly altering the superconducting behavior as resolved by magnetic susceptibility and electrical/thermal transport measurements. As a result, long-range magnetic ordering was observed below 12 K with neutron diffraction measurements. This work has implications for the design of magnetic superconductors for the fundamental understanding of superconductivity and magnetism in the iron chalcogenide system as well as exploitation as functional materials for next generation devices. arXiv:1912.09329v1 [cond-mat.supr-con]

Doping effects of transition metals on the superconductivity of (Li,Fe)OHFeSe films*

“…Recent neutron diffraction experiment has shown that the doped Mn exclusively occupies the Fe-sites in the hydroxide layers of deuterated (Li 0.875 Fe 0.062 Mn 0.062 OD)FeSe single crystal. [28] Previous theoretical model calculation has also shown that the electronic structure of (Li,Fe)OHFeSe is hardly affected by the magnetic dopants (Mn, Co) in the interlayers. [34] We note that superconductivity of the TMdoped (Li,Fe)OHFeSe is much less sensitive to the doping than that of the TM-doped binary FeSe superconductors reported previously: [30][31][32][33] The superconductivity (with T c > 35 K) still survives in the doped (Li,Fe)OHFeSe films at the highest x levels, sharply contrasting with the cases of Fe 1.01−x Cu x Se [31] and Fe 1−x Co x Se [33] where the superconductivity is killed by the Cu/Co doping of merely 1.5/3.6%.…”

“…Previous results have shown that the Mn doping can affect the superconducting critical temperature (T c ) to certain extent in the (Li,Fe)OHFeSe single crystals. [26][27][28] It is desirable to further study the interplay between the interlayer doping of various TMs and the superconductivity in the (Li,Fe)OHFeSe system.…”

“…The higher doping levels achieved for Mn (x up to 13.9%) and Co (6.7%) adjacent to Fe demonstrate that the (Li,Fe)OHFeSe structure accommodates them more easily than Ni (3.5%) and Cu (2.5%). Recent neutron diffraction experiment has shown that the doped Mn exclusively occupies the Fe-sites in the hydroxide layers of deuterated (Li 0.875 Fe 0.062 Mn 0.062 OD)FeSe single crystal [28]. Previous theoretical model calculation has…”

Recent progress on epitaxial growth of Fe-based superconducting thin films

“…Cu, Ni, Co, and Mn were tested as substitutes for Fe. They are homogeneously distributed and, according to neutron diffraction on Mn-doped deuterated single crystals [47], predominantly exchange the Fe in the (Li,Fe)OH layers. For all these substitutes, a T c reduction of 0.5 K % −1 was found, figure 2(a).…”

Probing Phosphorus Solubility and Its Effect on Critical Temperature (Tc) in the Helical Superconducting Magnet RbEuFe4As4–xPx

“…The discovery of layered, Eu-containing compounds of composition AEuFe 4 As 4 (A = Rb, Cs) (1144 compounds, for short) has introduced new members to the family of materials that display superconductivity coexisting with a three-dimensional long-range local moment magnetic order. − Eu 2+ ions carry a large, spin-only moment of 7 μ B and enter a long-range ordered state at T N = 15 K. The moments have an easy-plane anisotropy and order ferromagnetically within one Eu-plane and exhibit a helical stacking with a period of four c -axis lattice constants along the c -axis. , The superconducting transition occurs at T c ∼ 36.5–37.0 K. − , Next to EuFe 2 As 2 -derived materials and the family of (Li 1– x M x )­OH-intercalated FeSe (M = Fe, Mn, Co; T c = 43 K), , RbEuFe 4 As 4 has the highest T c of any magnetic superconductor. The Eu–Fe-based 1144 superconductors are unique because they simultaneously display two mutually antagonistic physical orders, high magnetic ordering, and superconductivity, implying sizable magnetic exchange interactions in the presence of strong superconducting pairing.…”