Electric-field breakdown of the insulating charge-ordered state in LuFe₂O₄ thin films

We have studied the dielectric breakdown of the insulating charge-ordered state and the associated current switching phenomenon in layered ferrite LuFe₂O₄. To elucidate the correlation between the ordering pattern and current switching behaviour, we synthesized highly c-axis oriented thin films by pulsed-laser deposition. An enhanced switching effect was achieved in the three-dimensional charge-ordered phase below ∼310 K, but not in the high-temperature two-dimensional phase. High-field transport measurements revealed that collective depinning of localized charge carriers is essential to induce switching. The lack of collective charge motion is proposed as the origin of the switching suppression in the two-dimensional phase.