TY - JOUR
T1 - Revisiting the mechanism of reversed thermoremanent magnetization based on observations from synthetic ferrian ilmenite (y = 0.7)
AU - Lagroix, France
AU - Banerjee, Subir K.
AU - Moskowitz, Bruce M.
PY - 2004/12/10
Y1 - 2004/12/10
N2 - This study investigates the magnetic behavior of three well-characterized synthetic single-phase ferrian ilmenite (y = 0.7) specimens over the temperature range between 10 K and 573 K. Careful experiments measuring induced and remanent magnetizations in variable temperatures, applied magnetic fields, and pretreatment conditions are conducted in order to elucidate the mechanism leading to reversed thermoremanent magnetization (RTRM). Magnetic ordering temperatures of the cation ordered domains, in all three samples, are estimated at 380 K, suggesting that their Curie temperatures (TC) are independent of the sample's thermal history. This is not the case for cation disordered boundaries resulting from quenching from high temperatures. These cation disordered domains have estimated magnetic ordering temperatures of 418 K (Q1300), 410 K (Q1050), and 425 K (Q900). The data unambiguously support a less than perfect ferrimagnetic-antiferromagnetic exchange interaction as the fundamental source of RTRM. Furthermore, the magnetic field strength of the "effective" exchange anisotropies in such polycrystalline samples are estimated at ∼2.7 mT (Q1300), ∼12 mT (Q1050), and 0 mT (Q900). However, from the results presented herein we conclude that favorable conditions for the acquisition of RTRM are dependent not only on the strength of the exchange anisotropy but also on the crucial role played by the size of the cation ordered domains.
AB - This study investigates the magnetic behavior of three well-characterized synthetic single-phase ferrian ilmenite (y = 0.7) specimens over the temperature range between 10 K and 573 K. Careful experiments measuring induced and remanent magnetizations in variable temperatures, applied magnetic fields, and pretreatment conditions are conducted in order to elucidate the mechanism leading to reversed thermoremanent magnetization (RTRM). Magnetic ordering temperatures of the cation ordered domains, in all three samples, are estimated at 380 K, suggesting that their Curie temperatures (TC) are independent of the sample's thermal history. This is not the case for cation disordered boundaries resulting from quenching from high temperatures. These cation disordered domains have estimated magnetic ordering temperatures of 418 K (Q1300), 410 K (Q1050), and 425 K (Q900). The data unambiguously support a less than perfect ferrimagnetic-antiferromagnetic exchange interaction as the fundamental source of RTRM. Furthermore, the magnetic field strength of the "effective" exchange anisotropies in such polycrystalline samples are estimated at ∼2.7 mT (Q1300), ∼12 mT (Q1050), and 0 mT (Q900). However, from the results presented herein we conclude that favorable conditions for the acquisition of RTRM are dependent not only on the strength of the exchange anisotropy but also on the crucial role played by the size of the cation ordered domains.
KW - Exchange anisotropy
KW - Ferrian ilmenite
KW - Reversed thermoremanent magnetization
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U2 - 10.1029/2004JB003076
DO - 10.1029/2004JB003076
M3 - Article
AN - SCOPUS:14244268504
SN - 2169-9313
VL - 109
SP - 1
EP - 13
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
IS - 12
M1 - B12108
ER -