Effect of Ag Addition on Microstructure and Raman Vibrational Modes of Bulk FeSe

Fabitha, K.; Rao, M. S. Ramachandra; Muralidhar, M.; Furutani, K.; Murakami, Masato

doi:10.1007/s10948-017-4117-2

“…The third sample, FeSe 0.94 (S2), was obtained by the solid state reaction (SSR) method [29]. Silver has been widely used as a dopant or additive to improve the microstructure and SC properties [53][54][55]. The role of Ag addition on structure and SC properties was investigated for polycrystalline Sr 0.6 K 0.4 Fe 2 As 2 [56] and FeSe 0.5 Te 0.5 [57],…”

Section: Methodsmentioning

confidence: 99%

Fluctuating Cooper pairs in FeSe at temperatures exceeding double Tc

Solovjov,

Petrenko,

Omelchenko

et al. 2020

Preprint

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Temperature dependencies of excess conductivity, σ ′ , have been studied in detail for three FeSe 0.94 textured polycrystalline samples prepared by partial melting and solid state reaction.It was revealed that both σ ′ and its temperature dependence are extremely sensitive to the method of sample preparation. Then, it was shown that in the range from the superconducting transition temperature T c ∼ 9 K up to the characteristic temperature T 01 ∼ 19 K, σ ′ (T ) obeys the classical fluctuation theories of Aslamazov-Larkin (AL) and Hikami-Larkin (Maki-Thompson (MT) term) pointing to the existence of fluctuating Cooper pairs in FeSe at temperatures exceeding double T c . Like in cuprates, AL-MT crossover at T 0 < T 01 is observed, which means the appearance of 3D-2D dimensional transition at this temperature. This allows us to determine the coherence length along the c-axis, ξ c (0) ∼ 3 Å, and a set of additional samples' parameters, including the phase relaxation time, τ φ , of fluctuating Cooper pairs, within a simple two-dimensional free-carrier picture. It was shown that τ φ in FeSe coincides with that found for YBa 2 Cu 3 O 7−δ suggesting that the nature of superconducting fluctuations is very similar for these high-temperature superconductors of different types.

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“…The third sample, FeSe 0.94 (S2), was obtained by the solid state reaction (SSR) method [29]. Silver has been widely used as a dopant or additive to improve the microstructure and SC properties [53][54][55]. The role of Ag addition on structure and SC properties was investigated for polycrystalline Sr 0.6 K 0.4 Fe 2 As 2 [56] and FeSe 0.5 Te 0.5 [57], where a small amount of Ag was found to enter into the crystal structure.…”

Section: Methodsmentioning

confidence: 99%

Fluctuating Cooper pairs in FeSe at temperatures exceeding double T _c

Solovjov

¹

,

Petrenko

²

,

Omelchenko

³

et al. 2020

Supercond. Sci. Technol.

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Temperature dependencies of excess conductivity, σ ′ , have been studied in detail for three FeSe0.94 textured polycrystalline samples prepared by partial melting and solid state reaction. It was revealed that both σ ′ and its temperature dependence are extremely sensitive to the method of sample preparation. Then, it was shown that in the range from the superconducting transition temperature T c ~9 K up to the characteristic temperature T 01 ~19 K, σ ′ ( T ) obeys the classical fluctuation theories of Aslamazov–Larkin (AL) and Hikami-Larkin (Maki-Thompson (MT) term) pointing to the existence of fluctuating Cooper pairs in FeSe at temperatures exceeding double T c . Like in cuprates, AL–MT crossover at T 0 < T 01 is observed, which means the appearance of 3D–2D dimensional transition at this temperature. This allows us to determine the coherence length along the c-axis, ξ c (0) ~3 Å, and a set of additional samples’ parameters, including the phase relaxation time, τ ϕ , of fluctuating Cooper pairs (FCPs), within a simple two-dimensional free-carrier picture. It was shown that τ ϕ in FeSe coincides with that found for YBa2Cu3O 7 − δ suggesting that the nature of superconducting fluctuations is very similar for these high-temperature superconductors of different types.

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“…The calculated Raman spectrum for hexagonal FeSe is also given (Figure S6b). Only the E 2g mode (around 250 cm –1 ) for hexagonal FeSe is Raman active, in contrast to Fe 7 Se 8 with several Raman active modes (A 1 and E). Therefore, the Fe 7 Se 8 phase can be separated from the hexagonal FeSe through Raman spectra.…”

mentioning

confidence: 93%

Two-Dimensional Room-Temperature Magnetic Nonstoichiometric Fe₇Se₈ Nanocrystals: Controllable Synthesis and Magnetic Behavior

Zhao

¹

,

Zhou

²

,

Liu

³

et al. 2022

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Two-dimensional (2D) magnetic materials have attracted significant attention for promising applications in energy-saving logic and robust memory devices. However, most 2D magnets discovered so far typically feature drawbacks for practical applications due to low critical temperatures. Herein, we synthesize ultrathin room-temperature (RT) magnetic Fe7Se8 nanoflakes via the space-confined chemical vapor deposition method. It is found that the appropriate supply and control of Se concentration in the reaction chamber is crucial for synthesizing high-quality nonstoichiometric Fe7Se8 nanoflakes. Cryogenic electrical and magnetic characterizations reveal the emergence of spin reorientation at ∼130 K and the survival of long-range magnetic ordering up to room temperature. The RT magnetic domain structures with different thicknesses are also uncovered by magnetic force microscopy. Moreover, theoretical calculations confirm the spin configuration and metallic band structure. The outstanding characteristics exhibited by Fe7Se8 nanoflakes, including RT magnetism, spin reorientation property, and good electrical conductivity, make them a potential candidate for RT spintronics.

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Effect of Ag Addition on Microstructure and Raman Vibrational Modes of Bulk FeSe

Cited by 22 publications

References 40 publications

Fluctuating Cooper pairs in FeSe at temperatures exceeding double Tc

Fluctuating Cooper pairs in FeSe at temperatures exceeding double Tc

Fluctuating Cooper pairs in FeSe at temperatures exceeding double T _c

Two-Dimensional Room-Temperature Magnetic Nonstoichiometric Fe₇Se₈ Nanocrystals: Controllable Synthesis and Magnetic Behavior

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Effect of Ag Addition on Microstructure and Raman Vibrational Modes of Bulk FeSe

Cited by 22 publications

References 40 publications

Fluctuating Cooper pairs in FeSe at temperatures exceeding double Tc

Fluctuating Cooper pairs in FeSe at temperatures exceeding double Tc

Fluctuating Cooper pairs in FeSe at temperatures exceeding double T c

Two-Dimensional Room-Temperature Magnetic Nonstoichiometric Fe7Se8 Nanocrystals: Controllable Synthesis and Magnetic Behavior

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Product

Resources

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Fluctuating Cooper pairs in FeSe at temperatures exceeding double T _c

Two-Dimensional Room-Temperature Magnetic Nonstoichiometric Fe₇Se₈ Nanocrystals: Controllable Synthesis and Magnetic Behavior