Magnetic characteristics of synthetic pseudo-single-domain and multi-domain greigite (Fe₃S₄)

We report the magnetic properties of pure synthetic pseudo-single-domain (PSD) and multi-domain (MD) greigite and the grain size dependence of the magnetic properties of greigite for the first time. The dominantly PSD-like and MD-like behavior are demonstrated by hysteresis, first-order reversal curve diagrams, low-temperature cycling (LTC) of room temperature saturation isothermal remanent magnetization (SIRM) and low-temperature SIRM warming curves. Variations in a range of magnetic properties clearly correlate with grain size. Characteristic PSD/MD behavior is preserved at low temperatures, which, coupled with the small decrease in remanence during warming, rule out the presence of substantial superparamagnetic behavior in the studied samples. LTC-SIRM measurements indicate a continuous demagnetization of remanence during cooling. Knowledge of this expanded range of magnetic properties of greigite should be widely useful in environmental magnetic and paleomagnetic studies.