Efficient Current-Induced Domain-Wall Displacement in ${\mathrm{SrRuO}}_3$

We demonstrate current-induced displacement of ferromagnetic domain walls in submicrometer fabricated patterns of ${\mathrm{SrRuO}}_3$ films. The displacement, monitored by measuring the extraordinary Hall effect, is induced at zero applied magnetic field and its direction is reversed when the current is reversed. We find that current density in the range of ${10}^9–{10}^{10}\mathrm{A}/{\mathrm{m}}^2$ is sufficient for domain-wall displacement when the depinning field varies between 50 to 500 Oe. These results indicate relatively high efficiency of the current in displacing domain walls which we believe is related to the narrow width ($\sim 3\mathrm{nm}$) of domain walls in this compound.

Figure 1

(a) Image of magnetic domains in ${\mathrm{SrRuO}}_3$ with transmission electron microscope in Lorentz mode (taken from [15]). Bright and dark lines image domain walls at which electron beam converges or diverges, respectively. Background features are related to buckling of the film and are not related to magnetic variations. (b) SEM image of the patterned sample. Current pulses are injected between $A$ and $B$ (perpendicular to the domain walls) and the average magnetization is sensed by measuring the extraordinary Hall effect between C and D and between E and F.

Figure 2

Normalized EHE ($R_{\mathrm{EHE}}^{*}$) measured with terminals CD ($R_{\mathrm{CD}}^{*}$) and terminals EF ($R_{\mathrm{EF}}^{*}$) as a function of positive and negative current pulses (100 ms) at $T=120\mathrm{K}$. In the initial state there is a single domain wall in the middle of the narrow constriction. The right side of the graph shows the change in $R_{\mathrm{CD}}^{*}$ and $R_{\mathrm{EF}}^{*}$ when pulses are applied from $A$ to $B$. The left side of the graph starts from the same initial position and it shows the change in $R_{\mathrm{CD}}^{*}$ and $R_{\mathrm{EF}}^{*}$ when pulses are applied from $B$ to $A$. The measurements are performed with a field of 50 Oe.

Figure 3

Current-induced hysteresis loop with current pulses (100 ms) at $T=140\mathrm{K}$ and $H=0$ measured with normalized EHE ($R_{\mathrm{EHE}}^{*}$).

Figure 4

(a) Characteristic measured depinning current, $J_c$, as a function of temperature (circles) and calculated $J_c$ based on [13] (squares). (b) Normalized EHE as a function of applied field. The characteristic critical depinning field, $H_c$, for each temperature is defined as the point at which the normalized EHE is 0.5.

Figure 5

$H_c/J_c$ as a function of temperature in ${\mathrm{SrRuO}}_3$ (circles), Py (squares), and ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$ (triangle). The data point for Py is deduced from Ref. 4 and the data points for ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$ are deduced from Ref. 10.