Tuning superconductivity in Eu(Fe<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mrow><mml:mn>0.81</mml:mn></mml:mrow></mml:msub></mml:math>Co<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mrow><mml:mn>0.19</mml:mn></mml:mrow></mml:msub></mml:math>)<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>As<mml:math xmlns:m

Tran, V.H.; Zaleski, T. A.; Bukowski, Z.; Tran, Lan Maria; Zaleski, A. J.

doi:10.1103/physrevb.85.052502

Cited by 18 publications

(23 citation statements)

References 23 publications

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“…On the other hand, for H ⊥ c, T c (H ) rapidly decreases below H cr and levels off at a value of 1.07 K at higher fields. The relative decrease of T c (H ) for this field configuration is equal to 64%, and is substantially larger than that for H c. Very recently, we pointed out that the drop in T c (H ) of Eu(Fe 0.81 Co 0.19 ) 2 As 2 is associated with a weakness of the orbital pair-breaking effect [30]. We suggested that this phenomenon would account for FI-SC in Eu(Fe 0.81 Co 0.19 ) 2 As 2 .…”

Section: Electron Transport Propertiesmentioning

confidence: 64%

The electronic phase diagrams of the Eu(Fe_0.81Co_0.19)₂As₂superconductor

Tran

Bukowski²,

Tran³

et al. 2012

New J. Phys.

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The magnetic and superconducting properties of an Eu(Fe 0.81 Co 0.19 ) 2 As 2 single crystal are investigated by means of ac magnetic susceptibility, dc magnetization, specific heat, transverse resistivity and Hall effect measurements in magnetic fields up to 9 T, applied parallel and perpendicular to the c-axis. The compound exhibits the coexistence of magnetism and superconductivity (SC), characterized by structural distortion (SD) and/or spin-density-wave (SDW) ordering at T SD/SDW = 78 ± 4 K, cantedantiferromagnetic (C-AF) ordering at the Néel temperature T N = 16.5 ± 0.5 K and SC at the critical temperature T c = 5.3 ± 0.2 K at zero field. Upon applying fields both the C-AF and SC states evolve in an unconventional manner. Magnetic field distinctly affects the spin canting, resulting in separation of the C-AF into two new phases: the C-AF and ferromagnetic (F) ones. The unusual behavior of the SC state produces field-induced SC in the H ⊥c configuration as an outcome of the weakening orbital pair-breaking effect. From the experimental data we derive the field-temperature phase diagrams for Eu(Fe 0.81 Co 0.19 ) 2 As 2 . A comparison of experimental results is made with theory developed for type II superconductors and then some important thermodynamic parameters characteristic of the superconducting state of Eu(Fe 0.81 Co 0.19 ) 2 As 2 are deduced such as the specific heat jump at T c , C p (T c )/γ n T c , the electron-phonon coupling constant e-ph , the upper critical field H c2 , coherence length ξ , the Fermi wave-vector k F , effective mass m * , Hall mobility µ H , magnetic penetration depth and the Ginzburg-Landau parameter κ.

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Section: Electron Transport Propertiesmentioning

confidence: 64%

The electronic phase diagrams of the Eu(Fe_0.81Co_0.19)₂As₂superconductor

Tran

Bukowski²,

Tran³

et al. 2012

New J. Phys.

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“…17,18 To the best of our knowledge, so far the zero-resistivity state in Eu(Fe 1−x Co x ) 2 As 2 was only realized in the single crystals grown using Sn as the flux, but with relatively lower superconducting transition temperature (T sc ∼ 10 K). [19][20][21][22] In addition, the SDW order in the self-flux-grown crystals was found to be suppressed much faster upon Co doping than that in the Sn-flux-grown crystals. 17,20 It is quite clear that the physical properties of the Eu(Fe 1−x Co x ) 2 As 2 single crystals strongly depend on the growth techniques.…”

Section: Introductionmentioning

confidence: 91%

Phase diagram of Eu magnetic ordering in Sn-flux-grown Eu(Fe1−xCox)2As
Jin
¹
,
Xiao
²
,
Bukowski
³

et al. 2016
Phys. Rev. B
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The magnetic ground state of the Eu 2+ moments in a series of Eu(Fe1−xCox)2As2 single crystals grown from the Sn flux has been investigated in detail by neutron diffraction measurements. Combined with the results from the macroscopic properties (resistivity, magnetic susceptibility and specific heat) measurements, a phase diagram describing how the Eu magnetic order evolves with Co doping in Eu(Fe1−xCox)2As2 is established. The ground-state magnetic structure of the Eu 2+ spins is found to develop from the A-type antiferromagnetic (AFM) order in the parent compound, via the A-type canted AFM structure with some net ferromagnetic (FM) moment component along the crystallographic c direction at intermediate Co doping levels, finally to the pure FM order at relatively high Co doping levels. The ordering temperature of Eu declines linearly at first, reaches the minimum value of 16.5(2) K around x = 0.100(4), and then reverses upwards with further Co doping. The doping-induced modification of the indirect Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between the Eu 2+ moments, which is mediated by the conduction d electrons on the (Fe,Co)As layers, as well as the change of the strength of the direct interaction between the Eu 2+ and Fe 2+ moments, might be responsible for the change of the magnetic ground state and the ordering temperature of the Eu sublattice. In addition, for Eu(Fe1−xCox)2As2 single crystals with 0.10 x 0.18, strong ferromagnetism from the Eu sublattice is well developed in the superconducting state, where a spontaneous vortex state is expected to account for the compromise between the two competing phenomena.

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“…and cobalt-doping [8,9,[24][25][26][27] studies in EuFe 2 As 2 . In some cases, zero resistance could not be achieved down to 2 K [5,8,24].…”

mentioning

confidence: 99%

“…Simultaneously, the Eu 2+ spins turn to the c-axis at low temperatures [14,15], which leads to FM [7, 16, 17], helimagnetism [8] or spin canting [18,19], all with significant ferromagnetic component. The coexistence of SC and FM was later confirmed and further studied by various experimental techniques [20][21][22][23][24][25][26][27]; nevertheless, there were different explanations for the Eu-spin ordering [6,[28][29][30], questioning the existence of FMSCs in the EuFe 2 As 2 -related system.Owing to the delicate interplay between SC and Eu-spin ordering, the superconducting and magnetic transitions of the above possible FMSCs are rather subtle, and the chemical doping in EuFe 2 As 2 with different elements may be non-trivial. In the case of pressure-induced SC in EuFe 2 As 2 , different superconducting transitions with [5, 28] (or without [6]) re-entrant resistance were reported.…”

mentioning

confidence: 99%

Anomalous critical fields and the absence of Meissner state in Eu(Fe_0.88Ir_0.12)₂As₂crystals

et al. 2013

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We report electrical and magnetic measurements of an optimally doped Eu(Fe 0.88 Ir 0.12 ) 2 As 2 crystal which shows superconductivity at T sc = 22 K and magnetic ordering of the Eu 2+ spins below 20 K. The results suggest that the Eu 2+ spins lie flat ferromagnetically in the ab plane at T ab m = 20 K, and then tilt toward the c-axis at T tilt m = 17.4 K. The isothermal magnetization loop at low temperatures shows both ferromagnetic behavior and superconducting characteristics, unambiguously demonstrating the coexistence of ferromagnetism and superconductivity. The upper critical field measured is remarkably reduced, as compared to other Fe-based superconductors with the same T sc , and it exhibits abnormal temperature dependence featured by the existence of an inflection point around T ab m , where the anisotropy ratio γ (≡ H ab c2 /H c c2 ) shows a minimum value smaller than 1.0. These observations can be explained by a ferromagnetic exchange field of ∼30 T which tilts its direction toward the c-axis below T tilt m . The strong internal field, much higher than the intrinsic lower critical field expected, leads to the absence of Meissner state, which is confirmed by the magnetic measurements under ultra-low fields. IntroductionSuperconductivity (SC) and ferromagnetism (FM) are two antagonistic cooperative phenomena in solid-state systems, thus it is very rare that SC coexists with FM (or even other magnetic states with ferromagnetic component) in a single material 2 [1,2]. Such material showing both SC and ferromagnetic components was earlier called 'ferromagnetic superconductor' (FMSC) [1] or 'magnetic superconductor' [3]. Lorenz and Chu [4] classified this special material into two categories according to its superconducting transition temperature T sc and ferromagnetic transition temperature T m . When T m > T sc , it is termed 'superconducting ferromagnet'; and for T m < T sc , it is called an FMSC.Recently, possible FMSCs were found in the EuFe 2 As 2 -related system, where the Eu spins and the FeAs layers are respectively responsible for spontaneous magnetization and SC, by applying pressure [5,6] or by chemical doping with phosphorus [7], cobalt [8,9] and ruthenium [10]. The parent compound EuFe 2 As 2 undergoes two antiferromagnetic transitions at ∼20 and ∼195 K, respectively, corresponding to the Eu and the Fe sublattices [11,12]. The magnetic structure was revealed by a neutron diffraction study [13] which shows an A-type antiferromagnetism (AFM) for the Eu 2+ spins, and a stripe-like AFM (also called spindensity wave (SDW)) for the Fe magnetic moment. Both Eu and Fe moments are parallel to the crystallographic a-axis in the undoped EuFe 2 As 2 . SC at 5-30 K emerges when the Fe-site SDW is sufficiently suppressed, either by applying high pressures or by an extrinsic doping. Simultaneously, the Eu 2+ spins turn to the c-axis at low temperatures [14,15], which leads to FM [7, 16, 17], helimagnetism [8] or spin canting [18,19], all with significant ferromagnetic component. The coexistence of SC and FM ...

show abstract

Tuning superconductivity in Eu(Fe0.81Co0.19)2As

Cited by 18 publications

References 23 publications

The electronic phase diagrams of the Eu(Fe_0.81Co_0.19)₂As₂superconductor

The electronic phase diagrams of the Eu(Fe_0.81Co_0.19)₂As₂superconductor

Phase diagram of Eu magnetic ordering in Sn-flux-grown Eu(Fe1−xCox)2As
Jin
¹
,
Xiao
²
,
Bukowski
³

et al. 2016
Phys. Rev. B
Self Cite
29
2
46
0
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Anomalous critical fields and the absence of Meissner state in Eu(Fe_0.88Ir_0.12)₂As₂crystals

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Tuning superconductivity in Eu(Fe0.81Co0.19)2As

Cited by 18 publications

References 23 publications

The electronic phase diagrams of the Eu(Fe0.81Co0.19)2As2superconductor

The electronic phase diagrams of the Eu(Fe0.81Co0.19)2As2superconductor

Phase diagram of Eu magnetic ordering in Sn-flux-grown Eu(Fe1−xCox)2AsJin1, Xiao2, Bukowski3 et al. 2016Phys. Rev. BSelf Cite292460View full textAdd to dashboardCite

Anomalous critical fields and the absence of Meissner state in Eu(Fe0.88Ir0.12)2As2crystals

Contact Info

Product

Resources

About

The electronic phase diagrams of the Eu(Fe_0.81Co_0.19)₂As₂superconductor

The electronic phase diagrams of the Eu(Fe_0.81Co_0.19)₂As₂superconductor

Phase diagram of Eu magnetic ordering in Sn-flux-grown Eu(Fe1−xCox)2As
Jin
¹
,
Xiao
²
,
Bukowski
³

et al. 2016
Phys. Rev. B
Self Cite
29
2
46
0
View full text Add to dashboard Cite

Anomalous critical fields and the absence of Meissner state in Eu(Fe_0.88Ir_0.12)₂As₂crystals