Two dimensional Langmuir-Blodgett magnets

The susceptibility of quasi-two-dimensional magnets formed by the Langmuir-Blodgett deposition of manganese stearate on aluminium foil has been measured at several points between 20 K and 0.4 K. Large area samples of 101 and 11 layers were detected by a SQUID magnetometer. With the magnetic field parallel to the film we deduced an equivalent volume susceptibility of 6.4x10^-3 at 4.2 K. The signals from the multilayers were paramagnetic in nature and no evidence for a transition was found. Unfortunately the signal from a bilayer and monolayer were masked by contaminants on the substrate.<br/><br/>The magnetometer used a cold finger to which the sample was attached. This was then moved into the pick-up coil, which was a second order gradiometer capable of cancelling out the signal from the long (150 mm) substrates. The magnetometer was usefully capable of detecting a sample with a moment down to 5x10^-11 Am² but vibration noise restricted the magnetic field to below 10 mT,<br/><br/>New equations were developed to describe the magnetic signals from a cylindrical magnetised sample within a superconducting shield. They were developed for use on a micro-computer making it possible to simulate the signal from the sample.<br/><br/>The tt-A curves for Manganese stearate were also studied. The uncertainty in the measurement of tx using filter papers was studied and estimated to be 2%. The manganese stearate was observed to transfer by Y and forced-Z type dipping.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

1988

Author dc:creator

• Head, David Ian

Advisors dc:contributor.advisor

• Blott, B.
• Melville, D.