Hall Effect Study of the Metamagnetic Transition in the Sr₄(Ru_0.99Fe_0.01)₃O₁₀ Nanosheet

Sr₄(Ru_0.99Fe_0.01)₃O₁₀ shows a ferromagnetic (FM) transition at T_C ∼ 105 K with the magnetic easy axis in the ab plane, followed by a metamagnetic transition (MMT) at low temperatures when the magnetic field H is applied along the c axis, which is in sharp contrast to that of the pure Sr₄Ru₃O₁₀, where the easy axis is along the c axis and the MMT is in the ab plane. Here, we studied the MMT in the Sr₄(Ru_0.99Fe_0.01)₃O₁₀ nanosheet by the Hall effect. It was found that the ordinary Hall coefficient of Sr₄(Ru_0.99Fe_0.01)₃O₁₀ is almost the same as that of the pure Sr₄Ru₃O₁₀, while a sudden increase in the Hall resistance R_xy is observed below ∼50 K, above which the R_xy presents the conventional anomalous Hall effect up to T_C. Analysis of the results indicates that the MMT has no direct correlation to the electronic structure but closely relates to the magnetic moment locking, where the magnetic-field-induced breakdown of the locked moments is responsible for the MMT.