THE SUPERCONDUCTING SUSPENSION EFFECT
The levitation of a magnet above a superconductor, the Meissner Effect, is
well known. In October 1988, Huang and Peters of Lockheed and NASA respectively
announced a startling and almost accidental discovery that they had made while
investigating high temperature ceramic superconductors. This suspension
phenomena can be demonstrated with the help of the Suspension & Levitation
Kit from Colorado Superconductor Inc.
The Kit contains a special superconductor disk which we shall call the
Enhanced Flux Pinning (EFP) disk. A large, powerful neodymium rare earth magnet
has been provided to suspend the EFP disk. A parallel set of materials have also
been provided with the Kit to demonstrate the Meissner Effect for
comparison. The experimenter requires only a source of liquid nitrogen for this
- Completely immerse the EFP disk in a flat dish containing liquid
nitrogen. The styrofoam dish in your Kit's container will do adequately.
- The liquid nitrogen boils around the EFP disk. When the boiling
- Examine the large neodymium magnet, and mark the square face with ink.
This is the face through which the magnetic axis passes.
- Holding the magnet with the provided non-magnetic tweezers such that the
magnetic axis is vertical, slowly lower the magnet so that it just touches
the top of the immersed EFP disk.
- As the magnet approaches the EFP disk, there will be a momentary
resistance to its continued downward motion. This will cease when the magnet
is in contact with the EFP disk. This resistance is a manifestation of the
well-known Meissner Effect.
- Gradually withdraw the magnet upwards.
- The EFP disk should follow the magnet as it moves upwards and out of the
liquid nitrogen. Observe that there is a gap between the EFP disk and the
magnet. This is a gap that one would not observe in normal magnetic
- As the EFP disk warms, it will loose its superconductivity, and can no
longer be suspended under the magnet. It will drop.
This was a demonstration of the Suspension Effect in the new
high temperature ceramic superconductors. Figure 8 below illustrates the salient
features of this demonstration.
- The EFP disk is particularly sensitive to moisture. Please dry the disk
immediately after use.
- The large neodymium rare earth magnet is very brittle. This powerful
magnet will abruptly adhere to ferromagnetic materials, or to the small
neodymium magnet provided with kit. This impact can easily chip or shatter the
- The EFP disk may shatter if it falls on a hard surface after the
Suspension effect ceases. Please take care to suspend the disk over a soft
surface, or over the liquid nitrogen bath.
- The EFP disk is very cold. Do not attempt to handle it when it has been
withdrawn out of the liquid nitrogen bath. Also, do not attempt to catch it in
your hand when it falls when suspension ceases.
- Can you think of any way that the Suspension Effect can be prolonged?
- Why do you think that the Suspension Effect was not observed with the low
temperature superconductors of yesteryear?
- What are some potential applications of the Suspension Effect?
The EFP disk was fabricated using a different temperature cycle than that
used for making the normal superconductor disks. The EFP disk can also be made
by doping (alloying) the regular superconductor disk with a small amount of
The Meissner Effect cannot be used to explain the Suspension Effect. Several
alternative explanations have been advanced to explain this phenomena. One such
explanation invokes the pinning of magnetic flux lines by the superconductor
(hence our name, the Enhanced Flux Pinning disk). The magnetic field flux lines
are pinned to impurities or imperfections within the superconductor, and they
thus prevent the superconductor from moving in any direction relative to the
Send mail to
with questions or comments about this web site.
Revised March 21, 2001.
Copyright © 2001 Colorado Superconductor, Inc.