Evidence for TRM domain wall moments?

• Published in: Geophysical journal international Vol. 102; no. 2; pp. 359 - 364
• Main Authors: Worm, H.-U., Banerjee, S. K.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.1990; Blackwell
• Subjects: domain walls; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geophysics: general, magnetic, electric and thermic methods and properties; Internal geophysics; magnetite; thermoremanent magnetization; Thermal demagnetization; Curie point; Magnetic hysteresis; Magnetic multidomains; Curie temperature; Thermoremanent magnetization; Laboratory studies; Magnetite; Magnetic domains; Magnetic domain; Laboratory test; Models; Magnetic properties
• ISSN: 0956-540X; 1365-246X
• DOI: 10.1111/j.1365-246X.1990.tb04471.x

Multidomain ferro- and ferrimagnets carrying a thermoremanent magnetization (TRM) display a maximum in remanent magnetization just below the Curie temperature Tc when continuously demagnetized in zero field. We interpret this demagnetization peak to be indicative of the presence of TRM domain wall moments that grow in a small temperature interval (near Tc) upon heating where the domain wall volume increases at a rate faster than the decrease in spontaneous magnetization Msp. Hysteresis measurements in the vicinity of Tc on a single crystal of magnetite show that the spontaneous magnetization may be orders of magnitude smaller than the strong field magnetization measured in Ms/T curves. Micromagnetic calculations using experimentally determined Msp/T data suggest that the single domain (SD) threshold for magnetite can increase by more than an order of magnitude from room temperature to just below Tc in support of the domain wall moment model.