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Wang, Z.; Song, Youting; Shi, Hualin; Wang, Z. W.; Chen, Z.; Tian, Huanfang; Chen, G. F.; Guo, Jiangang; Yang, H. X.; Li, J. Q.

doi:10.1103/physrevb.83.140505

Cited by 232 publications

(161 citation statements)

References 21 publications

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“…Moreover, while the positions of the insulating features in the semiconducting and superconducting compounds are almost the same as those in AFI1 at high temperatures, suggesting that the features originate from the same AFI1 insulating phase, the charging behavior in the superconducting compound happens at the much lower temperature of 20 K. This could be attributed to the variations of insulating-region size in different compounds. For the superconductor, the phase separation should happen in a mesoscopic scale, in light of the vacancy-ordered or vacancy-disordered domains observed in previous TEM studies [10]. Indeed, as will be discussed in Sec.…”

Section: Phase Separation In Superconductingmentioning

confidence: 85%

“…Neutron-scattering studies found that the ordered magnetic moment could be as large as 3:3 B per iron cation [9], which is the largest among all the ferropnictides and ferrochalcogenides discovered so far. Further thermal-power and transmission-electronmicroscope (TEM) measurements were able to distinguish two antiferromagnetic insulating (AFI) phases of K x Fe 2Ày Se 2 : an ''AFI1'' phase, characterized by a positive thermal power and a superlattice-modulation wave vector (1=5, 3=5, 0), indexed using the tetragonal unit cell with lattice parameters of a ¼ 3:913 # A and c ¼ 14:10 # A and a space group I4=mmm, and an ''AFI2'' phase, characterized by a negative thermal power and a superlattice-modulation wave vector (1=4, 3=4, 0) [7,10]. Theoretically, these antiferromagnetic insulating compounds were proposed to be the parent compounds for the A x Fe 2Ày Se 2 superconductor [11,12].…”

Section: Introductionmentioning

confidence: 99%

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Electronic Identification of the Parental Phases and Mesoscopic Phase Separation ofKxFe2−ySe2Superconductors

et al. 2011

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The nature of the parent compound of a high-temperature superconductor (HTS) often plays a pivotal role in determining its superconductivity. The parent compounds of the cuprate HTSs are antiferromagnetically ordered Mott insulators, while those of the iron-pnictide HTSs are metals with spin-density-wave order. Here we report the electronic identification of two insulating parental phases and one semiconducting parental phase of the newly discovered family of K x Fe 2Ày Se 2 superconductors. The two insulating phases exhibit Mott-insulator-like signatures, and one of the insulating phases is even present in the superconducting and semiconducting K x Fe 2Ày Se 2 compounds. However, it is mesoscopically phaseseparated from the superconducting or semiconducting phase. Moreover, we find that both the superconducting and semiconducting phases are free of the magnetic and vacancy orders present in the insulating phases, and that the electronic structure of the superconducting phase could be developed by doping the semiconducting phase with electrons. The rich electronic properties discovered in these parental phases of the K x Fe 2Ày Se 2 superconductors provide the foundation for studying the anomalous behavior in this new class of iron-based superconductors.

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Section: Phase Separation In Superconductingmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Electronic Identification of the Parental Phases and Mesoscopic Phase Separation ofKxFe2−ySe2Superconductors

et al. 2011

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“…There is extensive empirical evidence that the SC phase occurs mesoscopically separated from the block AF insulator [23][24][25][26][27][28][29]. The block AF phase exists throughout the two-dimensional phase diagrams of A x Fe y Se 2 over wide variations in the alkali metal (0.77 x 0.98) and iron contents (1.48 y 1.65), with little change of T N [30].…”

Section: Introductionmentioning

confidence: 99%

Two spatially separated phases in semiconductingRb0.8Fe1.5S2

et al. 2014

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We report neutron scattering and transport measurements on semiconducting Rb 0.8 Fe 1.5 S 2 , a compound isostructural and isoelectronic to the well-studied A 0.8 Fe y Se 2 (A = K, Rb, Cs, Tl/K) superconducting systems. Both resistivity and dc susceptibility measurements reveal a magnetic phase transition at T = 275 K. Neutron diffraction studies show that the 275 K transition originates from a phase with rhombic iron vacancy order which exhibits an in-plane stripe antiferromagnetic ordering below 275 K. In addition, the stripe antiferromagnetic phase interdigitates mesoscopically with an ubiquitous phase with √ 5 × √ 5 iron vacancy order. This phase has a magnetic transition at T N = 425 K and an iron vacancy order-disorder transition at T S = 600 K. These two different structural phases are closely similar to those observed in the isomorphous Se materials. Based on the close similarities of the in-plane antiferromagnetic structures, moments sizes, and ordering temperatures in semiconducting Rb 0.8 Fe 1.5 S 2 and K 0.81 Fe 1.58 Se 2 , we argue that the in-plane antiferromagnetic order arises from strong coupling between local moments. Superconductivity, previously observed in the A 0.8 Fe y Se 2−z S z system, is absent in Rb 0.8 Fe 1.5 S 2 , which has a semiconducting ground state. The implied relationship between stripe and block antiferromagnetism and superconductivity in these materials as well as a strategy for further investigation is discussed in this paper.

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“…State-of-the-art atomic resolution Electron Energy Loss Spectroscopy (EELS) experiments have been carried out in a STEM by a number of different research groups to investigate chemical inhomogeneity in a range of compounds including LaFeAsO 1−x Fx [36] and Fe 1+y TexSe 1−x [37]. In addition, Wang et al have used lattice imaging in a TEM to investigate Fe vacancy ordering in KxFe 2−y Se 2 crystals [38]. However, these techniques rely on producing extremely thin samples without creating artefacts in the crystals under investigation.…”

Section: Overview Of Characterisation Techniquesmentioning

confidence: 99%

Analytical microscopy of iron-based superconducting materials

Speller¹,

Mousavi²,

Dudin³

2015

Novel Superconducting Materials

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Inhomogeneity and phase separation in unconventional superconducting materials is a topic of increasing interest, as the competition between phases with different types of ordering is thought to play an important role in the emergence of the high temperature superconducting state. A wide range of experimental techniques are available for investigating the crystallography of these complex materials, however the majority are bulk probes. Here we briefly review some spatially resolved techniques that are being used to investigate phase separation in ironbased superconductors, with a focus on analytic Scanning Electron Microscopy techniques and synchrotron-based Photoelectron Microscopy.

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Microstructure and ordering of iron vacancies in the superconductor systemKyFexSe
Z. Wang
¹
,
Youting Song
²
,
Hualin Shi
³

et al.

Cited by 232 publications

References 21 publications

Electronic Identification of the Parental Phases and Mesoscopic Phase Separation ofKxFe2−ySe2Superconductors

Electronic Identification of the Parental Phases and Mesoscopic Phase Separation ofKxFe2−ySe2Superconductors

Two spatially separated phases in semiconductingRb0.8Fe1.5S2

Analytical microscopy of iron-based superconducting materials

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Microstructure and ordering of iron vacancies in the superconductor systemKyFexSeZ. Wang1, Youting Song2, Hualin Shi3 et al.

Cited by 232 publications

References 21 publications

Electronic Identification of the Parental Phases and Mesoscopic Phase Separation ofKxFe2−ySe2Superconductors

Electronic Identification of the Parental Phases and Mesoscopic Phase Separation ofKxFe2−ySe2Superconductors

Two spatially separated phases in semiconductingRb0.8Fe1.5S2

Analytical microscopy of iron-based superconducting materials

Contact Info

Product

Resources

About

Microstructure and ordering of iron vacancies in the superconductor systemKyFexSe
Z. Wang
¹
,
Youting Song
²
,
Hualin Shi
³

et al.