Open AccessContinuous drift correction and separate identification of ferrimagnetic and paramagnetic contributions in thermomagnetic runs
Author(s) -
Mullender T. A. T.,
Velzen A. J.,
Dekkers M. J.
Publication year - 1993
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1993.tb06995.x
Subject(s) - thermomagnetic convection , curie temperature , ferrimagnetism , paramagnetism , physics , harmonic , harmonic analysis , magnetic field , magnetization , materials science , nuclear magnetic resonance , computational physics , mathematical analysis , mathematics , condensed matter physics , acoustics , ferromagnetism , quantum mechanics
SUMMARY The principle of a Curie balance was changed by using a sinusoidally cycling applied magnetic field instead of a fixed applied field. This was done with a horizontal translation type Curie balance. By cycling between field values B min and B mix , the output signal is amenable to Fourier analysis. Partial Fourier analysis yields the fundamental harmonic and the second harmonic, termed SIG 1 and SIG 2 respectively. These are related to the saturation magnetization ( M s ) by M S = 2 SIG 1 ‐ 8 SIG 2 [( B max + B min )/( B max ‐ B min )])/[A″(B max ‐B min )] and to the paramagnetic susceptibility ( χ par ) by χ par = 8 SIG 2 /[A″( B mix ‐ B mix ) 2 ], whereby A is a calibration constant. Through the Fourier analysis continuous drift correction is achieved simultaneously. A personal computer takes care of field control, temperature control and data acquisition in real time mode, as well as processing the data, to yield SIG 1 and SIG 2 . After the experiment, SIG 1 and SIG 2 are processed further with a separate transversal filtering program that improves the signal‐to‐noise ratio. The working temperature range of the adapted horizontal translation type Curie balance is between room temperature and 900°C. Its noise level corresponds to a magnetic moment of 2 ° 10 − ‐ 9 Am 2 , making it a very powerful tool for thermomagnetic analysis of weakly magnetic material. Examples demonstrating this potential of the device are shown.