Influence of interstitial Fe to the phase diagram of Fe1+yTe1−xSex single crystals

Sun, Yue; Yamada, T.; Pyon, Sunseng; Tamegai, T.

doi:10.1038/srep32290

Cited by 45 publications

(53 citation statements)

References 44 publications

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“…R H for the as-grown crystal rapidly increases with decreasing temperature, whereas for the 400 h-annealed crystal, the increasing trend weakens, and for the 600 h-annealed crystal it stabilizes to show rather plateau-like behavior. This result agrees with that in the previous report [4] and suggests that the multi-band coincide with T * ρ ab and T * ρ c , respectively. Additional insight into the anomalous R H was obtained by measuring the magnetoresistance (MR) for these crystals (x = 0.2) at several temperatures above T c ( Fig.…”

Section: Resultssupporting

confidence: 93%

“…The long-range AFM ordered state exists only in the range of 0 ≤ x ≤ 0.06 and the superconducting state emerges at x ≥ 0.08. The fact that the AFM and superconducting states do not coexist agrees with the recent report on Fe 1+y Te 1−x Se x [4], which implies that the static AFM order competes with super-conductivity in this system. However, a comparison of their results [4] with ours reveals some differences.…”

Section: Resultssupporting

confidence: 89%

“…The fact that the AFM and superconducting states do not coexist agrees with the recent report on Fe 1+y Te 1−x Se x [4], which implies that the static AFM order competes with super-conductivity in this system. However, a comparison of their results [4] with ours reveals some differences. First, the phase boundary is slightly different; it exists at approximately x = 0.07 in this study, whereas in the other study it is asserted as being at x = 0.05 [4].…”

Section: Resultssupporting

confidence: 89%

“…However, the existence of excess iron (represented as y in the above-mentioned formula) has thus far prevented the establishment of the true phase diagram of this system. Recently, an O 2 -annealing technique was developed to remove excess iron from the Fe 1+y Te 1−x Se x system; hence, this technique was employed to investigate its phase diagram [4]. This pioneering work showed that the antiferromagnetic (AFM) ordered phase exists only for x < 0.05 and bulk superconductivity emerges from x = 0.05, and that these two phases do not coexist with each other.…”

Section: Introductionmentioning

confidence: 99%

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Incoherent-coherent crossover and the pseudogap in Te-annealed superconductingFe1+yTe1−xSexrevealed by magnetotransport measurements

et al. 2019

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In this study, we conducted various magnetotransport measurements on Fe 1+y Te 1−x Se x single crystals from which excess iron was sufficiently removed. Our results revealed that crossover from the incoherent to the coherent electronic state and opening of the pseudogap occur at high temperatures (≈ 150 K for x = 0.2). This is accompanied by a more substantial pseudogap and the emergence of a phase with a multi-band nature at lower temperatures (below ≈ 50 K for x = 0.2) before superconductivity sets in. A comparison of these results with those of the as-grown (non-superconducting) samples implies that the coherent state accompanied by the pseudogap is needed for the occurrence of superconductivity in this system. arXiv:1904.13020v1 [cond-mat.supr-con]

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Section: Resultssupporting

confidence: 93%

Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Incoherent-coherent crossover and the pseudogap in Te-annealed superconductingFe1+yTe1−xSexrevealed by magnetotransport measurements

et al. 2019

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“…The non-metallic characteristic is caused by the localization effect from interstitial Fe [26,27]. After removing the interstitial Fe by annealing crystals in oxygen, we improved the quality and enhanced the T zero c to 14.2 K. In Fig.…”

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confidence: 94%

Tuning electronic properties of FeSe0.5Te0.5 thin flakes using a solid ion conductor field-effect transistor

et al. 2017

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Using a field-effect transistor (FET) configuration with solid Li-ion conductor (SIC) as gate dielectric, we have successfully tuned carrier density in FeSe0.5Te0.5 thin flakes, and the electronic phase diagram has been mapped out. It is found that electron doping controlled by SIC-FET leads to a suppression of the superconducting phase, and eventually gives rise to an insulating state in FeSe0.5Te0.5. During the gating process, the (001) peak in XRD patterns stays at the same position and no new diffraction peak emerges, indicating no evident Li + ions intercalation into the FeSe0.5Te0.5. It indicates that a systematic change of electronic properties in FeSe0.5Te0.5 arises from the electrostatic doping induced by the accumulation of Li + ions at the interface between FeSe0.5Te0.5 and solid ion conductor in the devices. It is striking that these findings are drastically different from the observation in FeSe thin flakes using the same SIC-FET, in which Tc is enhanced from 8 K to larger than 40 K, then the system goes into an insulating phase accompanied by structural transitions.

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Modulations in Superconductors: Probes of Underlying Physics

et al. 2023

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development of various modulations techniques, breakthroughs in quantum materials are achieved, such as the quantum anomalous Hall effect (AHE) in topological insulators, [1][2][3][4] gate-tuned roomtemperature ferromagnetism in 2D van der Waals materials, [5][6][7][8] and emergent magnetic monopoles in artificial spin ice. [9] Especially, as the quantum materials of particular interest with zero dissipation, superconductors have been intensively studied with advanced modulations, aiming to reveal a plethora of emergent phenomena in condensed matter physics, such as superconductor-to-insulator transitions (SIT), [10][11][12] intermediate bosonic metallic state, [13] Bose-Einstein condensation (BEC)-Bardeen-Cooper-Schrieffer (BCS) crossover, [14,15] and intertwined orders, [16][17][18] as well as to develop applications in quantum computing [19][20][21] and ultrasensitive detections. [22][23][24] The superconductivity composes of two ingredients, including the Cooper pairs, each formed by two electrons, and phase coherence among Cooper pairs. [25] Superconductors such as metals and alloys are in the weak-coupling regime, which is well understood by BCS theory. [26,27] However, the later discovered superconductors, including cuprates, iron-based superconductors, and heavy-fermion superconductors, are strongly correlated systems, where a widely accepted microscopic mechanism yet remains absent. Therefore, various modulations have been utilized for the ultimate understanding of these superconductors and routines for room temperature superconductivity. Traditional modulations, such as elemental substitution, annealing, and polarization-induced gating are usually accompanied by some severe problems, including discontinuity, disorders, and limited ranges. Recently, state-of-the-art techniques have been developed with improved convenience, increased capability, and unprecedented dimensionalities, enabling more thorough investigations of unconventional superconductors.As a manifestation, we take some examples discussed in this review in advance. The carrier density can be tuned more conveniently and continuously. The techniques of ionic field-effect transistor (iFET) and electric double-layer transistor (EDLT) surpass conventional methods limited by solid solubility or dielectric breakdown, which enables the more precise phase diagram and detailed scaling analysis at the quantum phaseThe importance of modulations is elevated to an unprecedented level, due to the delicate conditions required to bring out exotic phenomena in quantum materials, such as topological materials, magnetic materials, and superconductors. Recently, state-of-the-art modulation techniques in material science, such as electric-double-layer transistor, piezoelectric-based strain apparatus, angle twisting, and nanofabrication, have been utilized in superconductors. They not only efficiently increase the tuning capability to the broader ranges but also extend the tuning dimensionality to unprecedented degrees of freedom, including quantum fluctuations of...

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Influence of interstitial Fe to the phase diagram of Fe1+yTe1−xSex single crystals

Cited by 45 publications

References 44 publications

Incoherent-coherent crossover and the pseudogap in Te-annealed superconductingFe1+yTe1−xSexrevealed by magnetotransport measurements

Incoherent-coherent crossover and the pseudogap in Te-annealed superconductingFe1+yTe1−xSexrevealed by magnetotransport measurements

Tuning electronic properties of FeSe0.5Te0.5 thin flakes using a solid ion conductor field-effect transistor

Modulations in Superconductors: Probes of Underlying Physics

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