Study on Magnetic Behavior of Nd₈Fe₈₄Ti₂B₆ Nanocomposite by FORC Diagram

Systematic investigation was made on the magnetic property of a series of Nd₂Fe₁₄B/α-Fe nanocomposites prepared by crystallization of amorphous Nd₈Fe₈₄Ti₂B₆ ribbon at annealing temperatures in the range of 800-860 °C. Both remanence and energy product increase with increasing annealing temperature, reaching the maximum values at 850 °C. Coercivity remains around 5.5 kOe for the annealing temperatures above 800 °C. Although the smooth demagnetization curve indicates effective exchange coupling between the Nd₂Fe₁₄B/α-Fe dual phases, FORC diagram reveals the existence of α-Fe for the Nd₈Fe₈₄Ti₂B₆ ribbon annealed at 850 °C. In addition, the variation of microcoercivity at different locations indicates a distributed exchange interaction, which can be caused by the nonuniform microstructure. The magnetic property is also affected by the demagnetization effect caused by the particle shape, which is evidenced by the negative region in the first-order reversal curve (FORC) diagram.

Keywords:
nanocomposite; exchange coupling; microcoercivity