Systematic growth of BaFe2 −xNixAs2large crystals

Yanchao, Chen; Lu, Xingye; Wang, Meng; Luo, Huiqian; Li, Shiliang

doi:10.1088/0953-2048/24/6/065004

Cited by 94 publications

(124 citation statements)

References 24 publications

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“…For the experiments, sizable single crystals of BaFe 2−x Ni x As 2 grown by self-flux method 42 were co-aligned on several aluminum plates by hydrogen-free glue with both in-plane and out-of-plane mosaic less than 3…”

Section: Methodsmentioning

confidence: 99%

Electron doping evolution of the magnetic excitations in BaFe2−xNixAs2
Luo
¹
,
Lu
²
,
Zhang
³

et al. 2013
Phys. Rev. B
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We use inelastic neutron scattering (INS) spectroscopy to study the magnetic excitations spectra throughout the Brioullion zone in electron-doped iron pnictide superconductors BaFe2−xNixAs2 with x = 0.096, 0.15, 0.18. While the x = 0.096 sample is near optimal superconductivity with Tc = 20 K and has coexisting static incommensurate magnetic order, the x = 0.15, 0.18 samples are electronoverdoped with reduced Tc of 14 K and 8 K, respectively, and have no static antiferromagnetic (AF) order. In previous INS work on undoped (x = 0) and electron optimally doped (x = 0.1) samples, the effect of electron-doping was found to modify spin waves in the parent compound BaFe2As2 below ∼100 meV and induce a neutron spin resonance at the commensurate AF ordering wave vector that couples with superconductivity. While the new data collected on the x = 0.096 sample confirms the overall features of the earlier work, our careful temperature dependent study of the resonance reveals that the resonance suddenly changes its Q-width below Tc similar to that of the optimally hole-doped iron pnictides Ba0.67K0.33Fe2As2. In addition, we establish the dispersion of the resonance and find it to change from commensurate to transversely incommensurate with increasing energy. Upon further electron-doping to overdoped iron pnictides with x = 0.15 and 0.18, the resonance becomes weaker and transversely incommensurate at all energies, while spin excitations above ∼100 meV are still not much affected. Our absolute spin excitation intensity measurements throughout the Brillouin zone for x = 0.096, 0.15, 0.18 confirm the notion that the low-energy spin excitation coupling with itinerant electron is important for superconductivity in these materials, even though the high-energy spin excitations are weakly doping dependent.

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Section: Methodsmentioning

confidence: 99%

Electron doping evolution of the magnetic excitations in BaFe2−xNixAs2
Luo
¹
,
Lu
²
,
Zhang
³

et al. 2013
Phys. Rev. B
Self Cite
44
12
46
1
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“…We grew large single crystals of the overdoped iron arsenide superconductor BaFe 1.85 Ni 0.15 As 2 using a self-flux method 42 . BaFe 1.85 Ni 0.15 As 2 has a T c of 14 K, and is far away from the AF phase of the undoped BaFe 2 As 2 ( Fig.1(a)).…”

Section: Methodsmentioning

confidence: 99%

Polarized neutron scattering studies of magnetic excitations in electron-overdoped superconducting BaFe1.85Ni0.15As

et al. 2012

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We use polarized inelastic neutron scattering to study low-energy spin excitations and their spatial anisotropy in electron-overdoped superconducting BaFe1.85Ni0.15As2 (Tc = 14 K). In the normal state, the imaginary part of the dynamic susceptibility, χ ′′ (Q, ω), at the antiferromagnetic (AF) wave vector Q = (0.5, 0.5, 1) increases linearly with energy for E ≤ 13 meV. Upon entering the superconducting state, a spin gap opens below E ≈ 3 meV and a broad neutron spin resonance appears at E ≈ 7 meV. Our careful neutron polarization analysis reveals that χ ′′ (Q, ω) is isotropic for the in-plane and out-of-plane components in both the normal and superconducting states. A comparison of these results with those of undoped BaFe2As2 and optimally electron-doped BaFe1.9Ni0.1As2 (Tc = 20 K) suggests that the spin anisotropy observed in BaFe1.9Ni0.1As2 is likely due to its proximity to the undoped BaFe2As2. Therefore, the neutron spin resonance is isotropic in the overdoped regime, consistent with a singlet to triplet excitation.

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“…Therefore, nematic quantum critical fluctuations can be unambiguously measured along the (100) direction or the (110) direction in the overdoped regime. Single crystals of BaFe 2−x Ni x As 2 were grown by the self-flux method that has been reported elsewhere [26]. The orientations of the crystals were determined by xray Laue method and the samples were cut into thin plates along the desired directions by a diamond wire saw.…”

mentioning

confidence: 99%

Nematic Quantum Critical Fluctuations inBaFe2−xNixAs2
Liu
¹
,
Gu
²
,
Zhang
³

et al. 2016
Phys. Rev. Lett.
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We have systematically studied the nematic fluctuations in the electron-doped iron-based superconductor BaFe2−xNixAs2 by measuring the in-plane resistance change under uniaxial pressure. While the nematic quantum critical point can be identified through the measurements along the (110) direction as studied previously, quantum and thermal critical fluctuations cannot be distinguished due to similar Curie-Weiss-like behaviors. Here we find that a sizable pressure-dependent resistivity along the (100) direction is present in all doping levels, which is against the simple picture of an Ising-type nematic model. The signal along the (100) direction becomes maximum at optimal doping, suggesting that it is associated with nematic quantum critical fluctuations. Our results indicate that thermal fluctuations from striped antiferromagnetic order dominate the underdoped regime along the (110) direction. We argue that either there is a strong coupling between the quantum critical fluctuations and the fermions, or more exotically, a higher symmetry may be present around optimal doping.PACS numbers: 74.70. Xa, The normal-state electronic states in many iron-based superconductors show strong in-plane anisotropic properties that break the fourfold rotational symmetry of the lattice due to the presence of nematic order [1][2][3][4][5][6][7][8][9]. The nematic order is typically accompanied by a structural transition at T s following an antiferromagnetic (AF) transition at T N ≤ T s , except for FeSe where no AF order is found [10,11]. Both the AF order and the structural transition disappear around the optimal doping level, indicating the presence of magnetic and/or nematic quantum critical points (QCPs). While there is increasing evidence that the magnetic QCP may not exist in many materials [12][13][14][15][16], the nematic QCP has attracted more and more interest since nematic quantum fluctuations may induce an attractive pairing interaction and thus enhance or even lead to superconductivity [17][18][19].So far, the evidence for the nematic QCP is rather limited. It is shown that the nematic order may go through a zero-temperature order-to-disorder quantum phase transition as shown by elastoresistance [3,9], elastic constants [4,5], and Raman scattering [7,8]. The nematic susceptibility shows divergent behavior with the form of (1/T ) γ around optimal doping [3,5,[7][8][9]20]. However, the value of γ is found to be 1, which suggests that the nematic QCP may result in a mean-field scaling. In the underdoped regime, the nematic susceptibility above the thermal transition T s should show Curie-Weiss-like behavior according to the Landau theory of second-order phase transitions. Therefore, quantum nematic fluctuations seem to show no characteristics distinguishable from thermal fluctuations, which is rather strange since one always expects that quantum and thermal fluctuations within the same system give rise to different critical properties.It has been well accepted that the nematic order in iron pnictides is an Ising-type order...

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Systematic growth of BaFe_{2 −x}Ni_xAs₂large crystals

Cited by 94 publications

References 24 publications

Electron doping evolution of the magnetic excitations in BaFe2−xNixAs2
Luo
¹
,
Lu
²
,
Zhang
³

et al. 2013
Phys. Rev. B
Self Cite
44
12
46
1
View full text Add to dashboard Cite

Electron doping evolution of the magnetic excitations in BaFe2−xNixAs2
Luo
¹
,
Lu
²
,
Zhang
³

et al. 2013
Phys. Rev. B
Self Cite
44
12
46
1
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Polarized neutron scattering studies of magnetic excitations in electron-overdoped superconducting BaFe1.85Ni0.15As

Nematic Quantum Critical Fluctuations inBaFe2−xNixAs2
Liu
¹
,
Gu
²
,
Zhang
³

et al. 2016
Phys. Rev. Lett.
Self Cite
49
6
75
1
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Systematic growth of BaFe2 −xNixAs2large crystals

Cited by 94 publications

References 24 publications

Electron doping evolution of the magnetic excitations in BaFe2−xNixAs2Luo1, Lu2, Zhang3 et al. 2013Phys. Rev. BSelf Cite4412461View full textAdd to dashboardCite

Electron doping evolution of the magnetic excitations in BaFe2−xNixAs2Luo1, Lu2, Zhang3 et al. 2013Phys. Rev. BSelf Cite4412461View full textAdd to dashboardCite

Polarized neutron scattering studies of magnetic excitations in electron-overdoped superconducting BaFe1.85Ni0.15As

Nematic Quantum Critical Fluctuations inBaFe2−xNixAs2Liu1, Gu2, Zhang3 et al. 2016Phys. Rev. Lett.Self Cite496751View full textAdd to dashboardCite

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Systematic growth of BaFe_{2 −x}Ni_xAs₂large crystals

Electron doping evolution of the magnetic excitations in BaFe2−xNixAs2
Luo
¹
,
Lu
²
,
Zhang
³

et al. 2013
Phys. Rev. B
Self Cite
44
12
46
1
View full text Add to dashboard Cite

Electron doping evolution of the magnetic excitations in BaFe2−xNixAs2
Luo
¹
,
Lu
²
,
Zhang
³

et al. 2013
Phys. Rev. B
Self Cite
44
12
46
1
View full text Add to dashboard Cite

Nematic Quantum Critical Fluctuations inBaFe2−xNixAs2
Liu
¹
,
Gu
²
,
Zhang
³

et al. 2016
Phys. Rev. Lett.
Self Cite
49
6
75
1
View full text Add to dashboard Cite