Second magnetization peak effect, vortex dynamics and flux pinning in 112-type superconductor Ca0.8La0.2Fe1−xCoxAs2

Zhou, Wei; Xing, Xiangzhuo; Wu, Wenjuan; Zhao, Haijun; Shi, Zhixiang

doi:10.1038/srep22278

Cited by 74 publications

(107 citation statements)

References 56 publications

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“…4b. The fishtail effect has been observed in a wide variety of materials, including low-temperature superconductors, cuprates, MgB 2 , and iron-based superconductors 44,45 and associated with an equally wide variety of effects, including elastic-to-plastic crossovers, vortex order-disorder phase transitions, and vortex lattice structural transitions 44 . In fact, a previous study 46 reported the appearance of a fishtail in a pristine NbSe 2 crystal when the applied field was tilted 30° from the c -axis and attributed it to a vortex order-disorder transition.…”

Section: Resultsmentioning

confidence: 99%

Glassy Dynamics in a heavy ion irradiated NbSe2 crystal

Eley¹,

Khilstrom²,

Fotovat³

et al. 2018

Sci Rep

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Fascination with glassy states has persisted since Fisher introduced the vortex-glass as a new thermodynamic phase that is a true superconductor that lacks conventional long-range order. Though Fisher’s original model considered point disorder, it was later predicted that columnar defects (CDs) could also induce glassiness — specifically, a Bose-glass phase. In YBa2Cu3O7−x (YBCO), glassy states can cause distinct behavior in the temperature (T ) dependent rate of thermally activated vortex motion (S). The vortex-glass state produces a plateau in S(T ) whereas a Bose-glass can transition into a state hosting vortex excitations called double-kinks that can expand, creating a large peak in S(T ). Although glass phases have been well-studied in YBCO, few studies exist of other materials containing CDs that could contribute to distinguishing universal behavior. Here, we report on the effectiveness of CDs tilted ~30° from the c-axis in reducing S in a NbSe2 crystal. The magnetization is 5 times higher and S is minimized when the field is parallel to the defects versus aligned with the c-axis. We see signatures of glassiness in both field orientations, but do not observe a peak in S(T ) nor a plateau at values observed in YBCO. Finally, we discuss the possibility that competing disorder induces a field-orientation-driven transition from a Bose-glass to an anisotropic glass involving both point and columnar disorder.

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Section: Resultsmentioning

confidence: 99%

Glassy Dynamics in a heavy ion irradiated NbSe2 crystal

Eley¹,

Khilstrom²,

Fotovat³

et al. 2018

Sci Rep

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“…However, in superconductors also vortex dynamics leads to a time-dependent magnetization, hence complicating the analysis [48]. Nevertheless, as demonstrated previously for EuFe(As 1−x P x ) 2 [14], both phases can be separated by their opposite signs in the time-dependent behavior (for instance in the FCH-FCC curve, the difference between field-cooled heating and field-cooled cooling curves).…”

Section: A Evidence For a Spin Glassmentioning

confidence: 89%

Reentrant phases in electron-dopedEuFe2As2: Spin glass and superconductivity

et al. 2017

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We report evidence for a reentrant spin glass phase in electron-doped EuFe2As2 single crystals and first traces of the superconductivity re-entrance in optics. In the close-to-optimal doped Eu(Fe0.91Ir0.09)2As2 and Eu(Fe0.93Rh0.07)2As2 samples two magnetic transitions are observed below the superconducting critical temperature Tc ≈ 21 K: the canted A-type antiferromagnetic order of the Eu 2+ ions sets in around 17 K; the spin glass behavior occurs another 2 K lower in temperature. In addition, strong evidence for an additional transition is found far below the spin glass temperature. Our extensive optical and magnetic investigations provide new insight into the interplay of local magnetism and superconductivity in these systems and elucidate the effect of the spin-glass phase on the reentrant superconducting state.

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“…On the other hand, it has been also shown that the overall pinning properties of Fe-based superconductors have been successfully explained in terms of collective pinning and vortex creep [29][30][31][32][33][34]45,73]. Based on these considerations, in this section, we apply the collective pinning and creep model to our results and extract the trend in the dopingdependent Jc.…”

Section: Temperature Dependence Of Jcmentioning

confidence: 95%

“…(3) The second magnetization peak (SMP) in the MHL, characterized by a hump far below Hc2, is evident in most cases, which supports a high Jc of Fe-based superconductors under high magnetic fields. As for the origin of SMP, (i) a crossover from elastic creep to plastic creep [29][30][31][32][33][34] or (ii) the corresponding orderdisorder transition of the vortex lattice [35,36], (iii) a phase transition between a rhombic (at low H) and a high-H square vortex lattice [25,37,38], etc. have been put forth.…”

Section: Introductionmentioning

confidence: 99%

Doping-dependent critical current properties in K, Co, and P-doped BaFe2As2 single crystals

et al. 2017

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* Both authors contributed equally to this work.In order to establish the doping dependence of the critical current properties in the iron-based superconductors, the in-plane critical current density (Jc) of BaFe2As2-based superconductors, Ba1-xKxFe2As2 (K-Ba122), Ba(Fe1-xCox)2As2 (Co-Ba122), and BaFe2(As1-xPx)2 (P-Ba122) in a wide range of doping concentration (x) was investigated by means of magnetization hysteresis loop (MHL) measurements on single crystal samples. Depending on the dopant elements and their concentration, Jc exhibits a variety of magneticfield (H)-and temperature (T)-dependences. (1) In the case of K-Ba122, the MHL of the under-doped samples (x ≤ 0.33) exhibits the second magnetization peak (SMP), which sustains high Jc at high H and high T, exceeding 10 5 A/cm 2 at T = 25 K and µ0H = 6 T for x = 0.30. On the other hand, the SMP is missing in the optimally-(x ~ 0.36-0.40) and over-doped (x ~ 0.50) samples, and consequently Jc rapidly decreases by more than one order of magnitude, although the change in Tc is within a few K. (2) For Co-Ba122, the SMP is always present over the entire superconducting (SC) dome from the under-(x ~ 0.05) to the over-doped (x ~ 0.12) region. However, the magnitude of Jc significantly changes with x, exhibiting a sharp maximum at x ~ 0.057, which is a slightly under-doped composition among Co-Ba122. (3) For P-Ba122, the highest Jc is attained at x = 0.30 corresponding to the highest Tc composition. For the over-doped samples, the MHL is characterized by a SMP located close to the irreversibility field Hirr. Common to the three doping variations, Jc becomes highest at the under-doping side of the SC dome near the phase boundary between the SC phase and the antiferromagnetic/orthorhombic (AFO) phase. Also, the peak appears in a narrow range of doping, distinct from the Tc dome with broad maximum. These similarities in the three cases indicate that the observed doping dependence of Jc is intrinsic to the BaFe2As2-based superconductors. The scaling analysis of the normalized pinning force density fp as a function of the reduced magnetic field h = H/Hirr (Hirr: irreversibility field) shows that the peak in the pinning force position (hmax) depends on x, indicating a change in pinning with x. On the other hand, high-Jc samples always attain similar hmax values of 0.40-0.45 for all the dopants, which may suggest that a common pinning source causes the highest Jc. A quantitative analysis of the Tdependent Jc indicates that the two pinning mechanisms, namely, the spatial variations in Tc (referred to as Tc pinning) and the fluctuations in the mean free path (l pinning), are enhanced for the under-doped samples, which results in the enhancement of Jc. Possible origins for the different pinning mechanism are discussed in connection with the x-dependence of Tc, the residual resistivity, AFO domain boundaries, and a possible quantum critical point.

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Second magnetization peak effect, vortex dynamics and flux pinning in 112-type superconductor Ca0.8La0.2Fe1−xCoxAs2

Cited by 74 publications

References 56 publications

Glassy Dynamics in a heavy ion irradiated NbSe2 crystal

Glassy Dynamics in a heavy ion irradiated NbSe2 crystal

Reentrant phases in electron-dopedEuFe2As2: Spin glass and superconductivity

Doping-dependent critical current properties in K, Co, and P-doped BaFe2As2 single crystals

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