Large extraordinary Hall effect in ${\left[\text{Pt}/\text{Co}\right]}_5/\text{Ru}/{\left[\text{Co}/\text{Pt}\right]}_5$ multilayers

This Brief Report presents giant extraordinary Hall effect (EHE) in the Ru-mediated antiferromagnetically coupled ${\left[\text{Pt}/\text{Co}\right]}_5/\text{Ru}/{\left[\text{Co}/\text{Pt}\right]}_5$ multilayers (MLs) compared with those MLs without the Ru spacer. The enhancement of the EHE is attributed to the strong Ru/Co interface scattering. Through the variation in the Pt layer thickness and the temperature, we determine the relation between the Hall voltage and the longitudinal resistivity. It is found that the conventional scaling analysis has difficulties in consistently interpreting our data.

Figure 1

Dependence of extraordinary Hall resistivity ${\rho }_{xy}$ on perpendicularly applied magnetic field $H$ for three Pt layer thickness $t_{\text{Pt}}$ for sample series of S1 and S2.

Figure 2

(a) Hall coefficient $R_e$ and saturated longitudinal resistivity ${\rho }_{xx}$ as a function of Pt layer thickness $t_{\text{Pt}}$ for samples S1 and S2. (b) $R_e$ vs ${\rho }_{xx}$ for samples S1 and S2, where the lines are fits to Eq. (2).

Figure 3

Hall hysteresis loops at several different temperatures.

Figure 4

Coercivity $H_C$ and saturated magnetization $M_s$ (normalized to that at room temperature) vs temperature $T$. The inset shows the perpendicular and longitudinal hysteresis loops at room temperature.

Figure 5

Extraordinary Hall coefficient $R_e\left(T\right)$ vs the saturated longitudinal resistivity ${\rho }_{xx}\left(T\right)$. The solid line is the fit of Eq. (2). The inset is the temperature dependence of longitudinal and extraordinary resistivity where the lines are guided for eyes.