Unusual Field Dependence of the Anomalous Hall Effect in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>Ta</mml:mi><mml:mo>/</mml:mo><mml:mi>Tb</mml:mi><mml:mtext>−</mml:mtext><mml:mi>Fe</mml:mi><mml:mtext>−</mml:mtext><mml:mi>Co</mml:mi></mml:math>
M.D. Davydova, P.N. Skirdkov, K.A. Zvezdin, Jong-Ching Wu, Sheng-Zhe Ciou, Yi-Ru Chiou, Lin-Xiu Ye, Te-Ho Wu, Ramesh Chandra Bhatt, A.V. Kimel, A.K. Zvezdin
Abstract
Experimental studies of the anomalous Hall effect are performed for thin-film $\mathrm{Ta}/\mathrm{Tb}\text{\ensuremath{-}}\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Co}$ 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 $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Co}$ sublattice, which is a subject of the strong interaction with the $\mathrm{Ta}$ layer. This $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Co}$ 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.