Low-temperature magnetic behavior of titanomagnetites

Titanium substitution has a significant effect on the temperature dependence (5–300 K) of low-temperature saturation remanence and of initial susceptibility in synthetic and natural titanomagnetite (Fe3−xTixO4, 0≤x<0.7). Our results show that low-temperature magnetic properties of multidomain titanomagnetite are markedly influenced by the temperature dependence of intrinsic anisotropy, including the magnetic effects associated with isotropic points for x<0.4, rapid temperature changes in the anisotropy constants for x>0.4, and electronic and lattice relaxation phenomena over the entire titanomagnetite compositional range. These features produce diagnostic magnetic behavior useful for titanomagnetite identification in natural samples. Moreover, the apparent similarities between the thermal decay of low-temperature remanence of titanomagnetite with pyrrhotite, pure magnetite, and superparamagnetic phases can lead to complications in interpreting low-temperature remanence data when titanomagnetite is present.