Magnetic levitation force and penetration depth in type-II superconductors

Journal Article · Sat Dec 31 23:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.51.424· OSTI ID:7060950

Xu, J H; Miller, Jr, J H; Ting, C S ^[1]

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1. Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204 (United States)

The superconducting levitation force [ital F] acting on a magnet placed above a type-II superconductor in both Meissner and mixed states is calculated as a function of temperature, based upon the London model. A simple relationship between the levitation force and the London penetration depth [lambda] is found. In particular, in the limit of [ital a]/[lambda][much gt]1, where [ital a] is the separation between the magnet and the superconductor, [ital F] varies linearly with [lambda], regardless of the shape of the magnet. The temperature dependences of [lambda] and [ital F] are examined for various superconducting pairing states, including [ital s]-wave, [ital d]-wave, and [ital s]+[ital id] states. It is found that, at low temperatures, both [lambda] and [ital F] show an exponential temperature dependence for [ital s]-wave, linear-[ital T] for [ital d]-wave, and [ital T][sup 2] dependence in a wide low-temperature range for the [ital s]+[ital id] state with a dominant [ital d]-wave component. The magnetic force microscope (MFM) is proposed to accurately measure the temperature-dependent levitation force. It is shown that the microscopic size of the MFM tip enables one to obtain the intrinsic temperature-dependent penetration depth of a single grain, in spite of the overall quality of the superconducting sample.

• OSTI ID: 7060950
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 51:1; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

665411* -- Basic Superconductivity Studies-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
D STATES
ENERGY LEVELS
EQUATIONS
LONDON EQUATION
MAGNETIC PROPERTIES
MIXED STATE
PENETRATION DEPTH
PHYSICAL PROPERTIES
S STATES
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
TYPE-II SUPERCONDUCTORS