J. Phys. C: Solid State Physics, Vol. 11 (1978) 1635-1650

Non-uniform magnetisation and the vibrating-sample magnetometer

C N Guy and W Howarth

A general treatment is given of the response of vibrating-sample 
magnetometer pick-up coils to non-uniformly magnetised specimens. It is 
shown that the nth term in a multiple expansion of the sample 
magnetsiation give reis to a component of the induced EFM at the 
oscillation frequency, proportional to tne (n+1)th derivative of the 
'pick-up field', h, along the direction of the sample motion (h is the 
field sucha that h*m is the flux produced in the coils by magnetic moment 
m). The analysis has been tested by observation of the signals produced by 
systems of small coils carrying DC current. To illustrate the method, 
experiments on the remanent states of several ordered magnetic materials 
are described. Application of the method, using a SQUID magnetometer, to 
the possible measurement of the sublattice magnetisation of 
antiferromagnetic materials is described.