Experimental studies of the anomalous Hall effect are performed for thin-film $\mathrm{Ta}/\mathrm{Tb}\text{−}\mathrm{Fe}\text{−}\mathrm{Co}$ over a wide range of temperatures and magnetic fields up to 3 T. Far from the compensation temperature ($T_{M}$ = 277 K), the field dependence has a conventional shape of a single hysteresis loop; just below the compensation point, the dependence is anomalous with the shape of a triple hysteresis. To understand this behavior, we experimentally reveal the magnetic phase diagram and theoretically analyze it in terms of spin-flop-like phase transitions. In this case, we observe the dominance of the $\mathrm{Fe}\text{−}\mathrm{Co}$ sublattice, which is a subject of the strong interaction with the $\mathrm{Ta}$ layer. This $\mathrm{Fe}\text{−}\mathrm{Co}$ anisotropy enhancement is expressed in the appearance of abnormal wing-shaped hysteresis loops near the compensation point and, in the unusual phase diagram, where the first-order phase transition line deviates towards low temperatures. This effect can be useful for the design of ultrafast ferrimagnetic devices with desired switching parameters.

• Received 2 September 2019
• Revised 16 January 2020
• Accepted 21 February 2020

DOI:https://doi.org/10.1103/PhysRevApplied.13.034053