HR: 13:40h
AN: GP23B-01 INVITED     [Abstracts]
TI: High-field Cantilever Magnetometery as a Tool for Single Crystal Magnetocrystalline Anisotropy Determination
AU: * Martin-Hernandez, F
EM: fatima@geo.uu.nl
AF: Paleomagnetic Laboratory "Fort Hoofddijk", Faculty of Geosciences, Utrecht University, Budapestlaan, 17, Utrecht, 3584 CD Netherlands
AU: Bominaar-Silken, I M
EM: I.Bominaar@science.ru.nl
AF: High Field Magnet Laboratory, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld,7, Nijmegen, 6525 ED Netherlands
AU: Dekkers, M J
EM: dekkers@geo.uu.nl
AF: Paleomagnetic Laboratory "Fort Hoofddijk", Faculty of Geosciences, Utrecht University, Budapestlaan, 17, Utrecht, 3584 CD Netherlands
AU: Maan, J C
EM: JC.Maan@science.ru.nl
AF: High Field Magnet Laboratory, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld,7, Nijmegen, 6525 ED Netherlands
AB: Torque magnetometry is utilized widely in physics and material science for the determination of magnetic properties in thin films and semiconductors. In rock magnetism, however, it has not yet been applied despite its great potential. In general, torque magnetometers are optimized for the specific problem at hand. Here, we use a cantilever magnetometer that allows measurement of samples with a volume up to 64 mm3, and that is inserted into an electromagnet with a maximum field of 2 T. The cantilever spring is suitable for torque values ranging from 7.5ú10-7 Núm to 40ú10-7 Núm, and it can be replaced easily by springs covering different ranges. The torque is detected capacitively; the measured capacitance is converted into torque by using a calibrated feedback coil. The magnetometer allows in-situ rotation of the sample in both directions and is, therefore, suitable to analyze e.g. rotational hysteresis effects. The magnetocrystalline anisotropy of octahedral magnetite single crystals of different sizes is evaluated. The anisotropy constants have been determined by Fourier analysis of the torque signal on the (111) plane and the (110) plane. The absolute anisotropy constant has been computed using the extrapolation-to-infinite-field method.
DE: 1518 Magnetic fabrics and anisotropy
DE: 1519 Magnetic mineralogy and petrology
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting