Magnetization and microwave study of superconducting MgB2

A. Dulčić, D. Paar, M. Požek, G. V. M. Williams, S. Krämer, C. U. Jung, Min-Seok Park, and Sung-Ik Lee
Phys. Rev. B 66, 014505 – Published 21 June 2002
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Abstract

We report magnetic-field-dependent magnetization and microwave impedance measurements on a MgB2 superconductor prepared by high-pressure synthesis. We find that the upper critical field is linearly dependent on temperature near Tc and the dc irreversibility field exponent is ∼1.4. Microwave surface impedance measurements were carried out in applied magnetic fields up to 8 T. The low-field data show an absence of weak links in the superconducting state. By inverting the surface impedance data, we find a vortex depinning frequency that decreases with increasing magnetic field, which is characteristic of collective pinning.

  • Received 17 July 2001

DOI:https://doi.org/10.1103/PhysRevB.66.014505

©2002 American Physical Society

Authors & Affiliations

A. Dulčić, D. Paar, and M. Požek

  • Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 331, HR-10002 Zagreb, Croatia

G. V. M. Williams

  • 2. Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart, Germany
  • Industrial Research Limited, P.O. Box 31310, Lower Hutt, New Zealand

S. Krämer

  • 2. Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart, Germany

C. U. Jung, Min-Seok Park, and Sung-Ik Lee

  • National Creative Research Initiative Center for Superconductivity and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea

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Vol. 66, Iss. 1 — 1 July 2002

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