Detection of the flux dynamical regimes in Bi4O4S3 by multiharmonic AC susceptibility

https://doi.org/10.1016/j.physc.2014.10.002Get rights and content

Highlights

  • •

    The first harmonic of the AC magnetic susceptibility reveals a bulk superconductivity.

  • •

    Both the first and the third harmonics of the AC magnetic susceptibility exhibit a nonlinear behaviour.

  • •

    The third harmonic confirms the existence of a critical state together with flux creep regime and non linear flux flow.

  • •

    The quantitative analysis of the activation energy and the critical current density confirm the presence of creep.

Abstract

The temperature dependent first and third harmonics of the AC magnetic susceptibility χ1,3(T) have been measured on Bi4O4S3. The χ1(T) magnetic response is due to the intergranular contribution with a transition temperature Tc ≈ 4.4 K. The dependencies of the χ3(T) on the AC field amplitude and frequency reveal a critical state with the presence of the flux creep and the flux flow regimes. In fact, the field dependencies of the effective activation energy and of the frequency dependent critical current density have been found to be described with power laws characteristic of the collective creep regime involving large flux bundles.

Introduction

High temperature superconductivity has been discovered in materials with a layered crystal structure in which the superconductivity can become a two-dimensional phenomenon achieving high transition temperatures and unconventional order mechanisms. The highest critical temperature Tc has been observed in cuprates, a family of Cu-oxide superconductors whose crystal structure is composed by CuO2 planes and spacer layers [1], [2], [3], [4], [5]. The other popular group of layered high-Tc superconductors is the Fe-based family, composed by a common block of FeX layers (where X = As, P, S, Se, or Te) and spacer layers [6], [7], [8], [9], [10], [11], [12], [13], [14], with Tc as high as 56 K.

A theoretical understanding of the superconductivity in the CuO2 and Fe-based high-Tc compounds is still not completed, but it is experimentally observed that in these systems the transition temperature depends in particular on the composition of the stacking structure. Thus, large effort is focused to obtain new superconducting layered compounds, in which the superconductivity mechanisms are similar to those of the cuprates and Fe-based superconductors, that could contribute to further explain such mechanisms and also to realize higher Tc superconductors for the applications.

In this regard bulk superconductivity has been recently observed in a new bismuth-oxysulfide layered compound Bi4O4S3 [15], [16], [17], that consists of a layered crystal structure based on stacking layers of BiS2 and Bi4O4(SO4)1−x, where x indicates the deficiency of SO42− ions at the interlayer sites. The Tc of Bi4O4S3 was found to be around 4.5 K, and other compounds with a layered structure based on the BiS2 layer and ReO1−xFx (La, Ce, Pr, Nd) block layers have been discovered with Tc ≈ 10 K [18], [19], [20], [21], [22], [23], [24]. The doping mechanism in these systems is similar to those of cuprates and Fe-based pnictides, suggesting that the BiS2 plays the role of the CuO2 layer in the cuprates and of the FeX layer in the Fe-based pnictides. Therefore new BiS2-based superconductors could be designed also to provide additional information for the comprehension of the superconductivity mechanisms in both cuprates and iron based superconductors.

In this work we report the study of the temperature dependence of the AC magnetic susceptibility measured on a Bi4O4S3 superconducting polycrystalline sample. Information about the electromagnetic granularity, the pinning mechanisms, and the superconducting parameters such as the critical temperature, the critical field, and the critical current density of Bi4O4S3 are obtained by analyzing the real and imaginary parts of the first and third harmonics of AC susceptibility. In particular, we will use a method described in Section 2 and based on the comparison of the measured AC susceptibility curves, and especially the 3rd harmonic, with the numerically simulated curves for samples with the same geometry, allowing us to detect the presence of flux dynamics and to determine the flux dynamic regimes governing the AC magnetic response. The detailed analysis of the experimental results in the framework of the detected flux creep regime allowed us to extract the temperature and the field dependences of the critical current density and the creep activation energy.

Section snippets

Method

The AC susceptibility (ACS) technique has been used, in general, to obtain information about the flux dynamical processes in the mixed state of type-II superconductors [25], [26]. It consists in applying a time dependent magnetic field on the sample, while acquiring, by the lock-in technique, the complex susceptibility χ=∑n(χn′+iχn″) where χn=χn′+iχn″ are the Fourier coefficients of the steady magnetization cycles.

Although the same kind of investigation can be performed by using different

Experimental results

A polycrystalline sample of Bi4O4S3 was prepared by the solid-state reaction method starting from Bi2S3, Bi2O3 powders and S grains and by using thermal treatments up to 510 °C [15].

The temperature dependence of both the first and the third ACS harmonics have been measured Bi4O4S3 sample by using the AC insert of a 9 T Quantum Design PPMS. The sample was a slab with dimensions 0.5 mm × 2 mm × 2 mm cut from a larger pellet.

The ACS measurements were performed by applying magnetic fields parallel to the

Discussion

A method based on the combined analysis of the measured 1st and 3rd ACS harmonics, and on the comparison of the measured curves of the 3rd harmonic with the numerical simulations obtained in presence of the different dissipative phenomena [47], [31], has been used to extract detailed information about the flux dynamic regimes governing the magnetic response of Bi4O4S3.

As already observed in the previous section, the dependence on the AC field amplitude of the curves of χ1T, measured at zero DC

Conclusions

In conclusion, we have measured the temperature dependent AC magnetic susceptibilities χ1 and χ3 of the Bi4O4S3 superconductor at different AC field amplitudes and frequencies, and with the superposition of different DC fields. From the analysis of the AC susceptibility first harmonic χ1(T) data we have established that the superconducting magnetic response of Bi4O4S3 is governed by the currents flowing around the whole sample through the intergrains links, that hide the eventual response

References (57)

  • J.Z. Bednorz et al.

    Phys. B Conden. Matter

    (1986)
  • M.K. Wu

    Phys. Rev. Lett.

    (1987)
  • H. Maeda

    Jpn. J. Appl. Phys.

    (1988)
  • A. Schilling

    Nature

    (1993)
  • L. Gao

    Phys. Rev. B

    (1994)
  • Y. Kamihara et al.

    J. Am. Chem. Soc.

    (2008)
  • X.H. Chen

    Nature

    (2008)
  • Z.A. Ren

    Chinese Phys. Lett.

    (2008)
  • M. Rotter et al.

    Phys. Rev. Lett.

    (2008)
  • F.C. Hsu

    Proc. Natl. Acad. Sci. USA

    (2008)
  • X.C. Wang

    Solid State Commun.

    (2008)
  • K.W. Yeh

    EPL 84

    (2008)
  • Y. Mizuguchi

    Appl. Phys. Lett.

    (2009)
  • J. Guo

    Phys. Rev. B

    (2010)
  • Y. Mizuguchi et al.

    Phys. Rev. B

    (2012)
  • S.K. Singh et al.

    J. Am. Chem. Soc.

    (2012)
  • R. Jha et al.

    Physica C

    (2014)
  • Y. Mizuguchi et al.

    J. Phys. Soc. Jpn.

    (2012)
  • S. Demura et al.

    J. Phys. Soc. Jpn.

    (2013)
  • R. Jha et al.

    J. Supercond. Nov. Magn.

    (2013)
  • J. Xing et al.

    Phys. Rev. B

    (2012)
  • C.I. Sathish, H.L. Feng, Y. Shi, K. Yamaura, 2013...
  • W.A. Phelan et al.

    J. Am. Chem. Soc.

    (2013)
  • C. Morice, E. Artacho, S.E. Dutton, D. Molnar, H.J. Kim, S.S. Saxena, arXiv:1305.1201v1,...
  • R.B. Goldfarb et al.
  • F. Gomory

    Supercond. Sci. Technol.

    (1997)
  • P.L. Gammel et al.

    Phys. Rev. Lett.

    (1998)
  • D.E. Farrel et al.

    Phys. Rev. Lett.

    (1991)
    • View full text
    Copyright © 2014 Elsevier B.V. All rights reserved.