Anomalous Hall effect with giant hysteresis loop inLa0.67Sr0.33MnO3|SrRuO3superlattices

We report anomalous Hall effects exhibiting a hysteresis loop as large as about 10 T in a ferromagnetic superlattice comprising ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_{3}$ and ${\mathrm{SrRuO}}_{3}$ layers. The superlattices grown by pulsed laser deposition exhibit a strong antiferromagnetic interlayer coupling below 110 K, where both ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_{3}$ and ${\mathrm{SrRuO}}_{3}$ layers show anomalous Hall effects. With increasing magnetic-field strength, the anomalous Hall resistivity in the superlattices changes its sign depending on the magnetization directions of the ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_{3}$ and ${\mathrm{SrRuO}}_{3}$ layers. As a consequence of competition among the antiferromagnetic interlayer coupling, the Zeeman effect, and magnetic anisotropies, the width of the hysteresis loop in the anomalous Hall resistivity in the superlattices becomes larger than 8 T at 10 K, clearly greater than those observed in ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_{3}$ and ${\mathrm{SrRuO}}_{3}$ single layer films.