Wohlleben Effect (paramagnetic Meissner Effect) in high-temperature superconductors

Journal Article · Fri Apr 01 04:00:00 EST 1994 · Journal of Low Temperature Physics

DOI:https://doi.org/10.1007/BF00754937· OSTI ID:102561

Khomskii, D ^[1]

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1. Groningen Univ. (Netherlands)

Recently a quite unexpected phenomenon was observed during the study of the magnetic properties of High-T{sub c} superconductors: In the field-cooled regime the magnetic response of some HTSC at very low fields ({le} 1 Oe), instead of being diamagnetic, becomes paramagnetic. Such behavior is perfectly reproducible and stable. This effect is now called the Wohlleben Effect. The samples showing the Wohlleben effect also display anomalous behavior in some other properties (microwave absorption, second harmonic of magnetic susceptibility). In this paper a survey is given of the experimental studies of this and related phenomena, carried out in different laboratories. Corresponding theoretical models are also discussed. The effect is attributed to the formation of spontaneous currents (spontaneous orbital magnetic moments) in the ground state of the weak link network in case when Josephson coupling between certain grains is negative ({pi}-contacts). Microscopic mechanisms of inverse Josephson coupling are discussed especially in connection with the possible unconventional pairing in HTSC.

• Sponsoring Organization: USDOE
• OSTI ID: 102561
• Report Number(s): CONF-9309321--
• Journal Information: Journal of Low Temperature Physics, Journal Name: Journal of Low Temperature Physics Journal Issue: 1-2 Vol. 95; ISSN JLTPAC; ISSN 0022-2291
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BISMUTH OXIDES
COPPER OXIDES
HIGH-TC SUPERCONDUCTORS
MAGNETIC PROPERTIES
MEISSNER-OCHSENFELD EFFECT
PARAMAGNETISM