Magnetic irreversibility: An important amendment in the zero-field-cooling and field-cooling method

The present work reports about experimental procedures to correct significant deviations of magnetization data, caused by magnetic relaxation, due to small field cycling by sample transport in the inhomogeneous applied magnetic field of commercial magnetometers. The extensively used method for measu...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2016-02, Vol.55 (2), p.23101
Main Authors: Dias, Fábio Teixeira, Vieira, Valdemar das Neves, Nunes, Sabrina Esperança, Pureur, Paulo, Schaf, Jacob, Farinela da Silva, Graziele Fernanda, Gouvêa, Cristol de Paiva, Wolff-Fabris, Frederik, Kampert, Erik, Obradors, Xavier, Puig, Teresa, Rovira, Joan Josep Roa
Format: Article
Language:English
Subjects:
Amplitudes
COOLING
COOLING CURVES
COPPER OXIDE
Displacement
ELECTRICAL CONDUCTIVITY
MAGNETIC FIELD
Magnetic fields
Magnetization
Magnetometers
SUPERCONDUCTIVITY
Transport
YTTRIUM OXIDE
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Summary:The present work reports about experimental procedures to correct significant deviations of magnetization data, caused by magnetic relaxation, due to small field cycling by sample transport in the inhomogeneous applied magnetic field of commercial magnetometers. The extensively used method for measuring the magnetic irreversibility by first cooling the sample in zero field, switching on a constant applied magnetic field and measuring the magnetization M(T) while slowly warming the sample, and subsequently measuring M(T) while slowly cooling it back in the same field, is very sensitive even to small displacement of the magnetization curve. In our melt-processed YBaCuO superconducting sample we observed displacements of the irreversibility limit up to 7 K in high fields. Such displacements are detected only on confronting the magnetic irreversibility limit with other measurements, like for instance zero resistance, in which the sample remains fixed and so is not affected by such relaxation. We measured the magnetic irreversibility, Tirr(H), using a vibrating sample magnetometer (VSM) from Quantum Design. The zero resistance data, Tc0(H), were obtained using a PPMS from Quantum Design. On confronting our irreversibility lines with those of zero resistance, we observed that the Tc0(H) data fell several degrees K above the Tirr(H) data, which obviously contradicts the well known properties of superconductivity. In order to get consistent Tirr(H) data in the H-T plane, it was necessary to do a lot of additional measurements as a function of the amplitude of the sample transport and extrapolate the Tirr(H) data for each applied field to zero amplitude.
ISSN:0021-4922
1347-4065
DOI:10.7567/JJAP.55.023101