Coexistence of magnetism and superconductivity in separate layers of the iron-based superconductor Li1−xFex(OH)Fe1−y

Abstract

The magnetic properties attributed to the hydroxide layer of Li1−xFex(OH)Fe1−ySe have been elucidated by the study of superconducting and non-superconducting members of this family of compounds. Both a.c. magnetometry and muon spin relaxation measurements of non-superconductors find a magnetic state existing below ≈ 10 K which exhibits slow relaxation of magnetisation. This magnetic state is accompanied by a low temperature heat capacity anomaly present in both superconducting and nonsuperconducting variants suggesting that the magnetism persists into the superconducting state. The estimated value of magnetic moment present within the hydroxide layer supports a picture of a glassy magnetic state, probably comprising clusters of iron ions of varying cluster sizes distributed within the lithium hydroxide layer.

(Li1−xFex)OHFeSe Superconductors: Crystal Growth, Structure, and Electromagnetic Properties

“…In [(Li 1−x Fe x )OH](Fe 1−y Li y )Se, superconductivity below T c = 43 K coexists with ferromagnetism below 10 K [83]. The study of SC and non-SC (Li 1−x Fe x )OHFe 1−y Se suggests a glassy magnetic state, probably comprising clusters of iron ions of varying cluster sizes distributed within the lithium hydroxide layer [92].…”

“…Crystals 2017, 7, 167 11 of 26 (Li1−xFex)OHFe1−ySe suggests a glassy magnetic state, probably comprising clusters of iron ions of varying cluster sizes distributed within the lithium hydroxide layer [92]. …”

A.C. susceptibility as a probe of low-frequency magnetic dynamics

“…Figure 18 shows the χ peaks associated with the reentrant spin glass La 0.8 Sr 0.2 Mn 0.925 Ti 0.075 O 3 . Another example is the low temperature spin-glass like state that occurs due to the presence of iron in the lithium hydroxide layers of Li 1−x Fe x (OH)Fe 1−y Se [82,83]. This compound displays spin glass-like slow magnetic relaxation that persists in the presence of the superconductivity in the iron selenide layers [83].…”

Tuning Fe–Se Tetrahedral Frameworks by a Combination of [Fe(en)3]2+ Cations and Cl– Anions

“…Many researchers have explored layered binary iron chalcogenides as parent compounds to understand their intercalation chemistry and structure–property relationships. − Increasing the interlayer distance and valence electron concentration by the introduction of electropositive cations such as Li + , Na + , K + , Ca 2+ , Sr 2+ , or Ba 2+ raises the T c to 30–46 K. − Intercalation of LiFe­(OH) layers between FeSe layers gives rise to layered materials with magnetic ordering at ∼12 K . Superconducting critical temperatures exceeding 40 K have been achieved by displacing Fe atoms from the LiFe­(OH) layers to occupy Fe site vacancies in the selenide layers. , While superconducting phases containing alkali metals and ammonia have been reported, there are few detailed structural reports for such compounds. Clarke et al reported the first reliable crystal structure determination of Li-ammonia intercalate in FeSe with T c as high as 43 K, as well as in situ characterization of the reactions of Li/NH 3 with FeSe using X-ray and neutron diffraction .…”