The phase transition of <i>ɛ</i>-In<i>x</i>Fe2−<i>x</i>O3 nanomagnets with a large thermal hysteresis loop (invited)

Abstract

A large thermal hysteresis loop was observed in the phase transition on rod-shaped ɛ-InxFe2−xO3 (x ∼ 0.04) nanomagnets. The width of the thermal hysteresis loop, ΔT, increased with increasing rod length (l), i.e., ΔT = 6 K (l = 25 nm), 14 K (40 nm), 25 K (80 nm), and 47 K (170 nm). The observed ΔT value of 47 K is one of the largest values among insulating ferromagnetic materials. The thermal hysteresis loops were analyzed by the Slichter and Drickamer model, and the results showed that the transition enthalpy and entropy do not change. However, the elastic interaction parameter between the transition sites increases with an increasing l value. Maybe the correlation length of a propagating phonon due to elastic interaction competes with the rod length of the samples, causing the rod-length dependence of the thermal hysteresis loop.