Observation of spin-glass-like behavior in ${\text{SrRuO}}_3$ epitaxial thin films

We report on the observation of spin-glass-like behavior and strong magnetic anisotropy in extremely smooth ($\sim 1–3\text{Å}$ roughness) epitaxial (110) and (010) ${\text{SrRuO}}_3$ thin films. The easy axis of magnetization is always perpendicular to the plane of the film (unidirectional) irrespective of crystallographic orientation. An attempt has been made to understand the nature and origin of spin-glass behavior, which fits well with Heisenberg model.

Figure 1

(Color online) XRD patterns of SRO (a) (110) and (b) (010) films grown on (100) and (110) STO substrates, respectively. XRD pattern of STO is given for comparison. The insets depict the schematic of the growth orientations of SRO films on (100) and (110) STO substrates.

Figure 2

(Color online) AFM images of SRO films on STO substrates. (a) [110] oriented SRO film on [100] STO substrate, (b) [010] oriented SRO film on [110] STO substrate, (c) and (d) are the three-dimensional (3D) autocorrelation images of the surfaces (a) and (b), respectively. The scan area was $2\times 2\mu {\text{m}}^2$.

Figure 3

(Color online) Temperature dependence of hysteresis $\left(M\text{−}B\right)$ loops of SRO films on STO substrates at different orientations: (a) (110) SRO film and (b) (010) SRO film.

Figure 4

(Color online) (a) ZFC and FC magnetizations of SRO films as a function of temperature at different orientations: (a) (110) SRO films and (b) (010) SRO film. The solid line on FC magnetizations is the curve fitted with $M\propto {\left(T_c-T\right)}^{\beta }$. The insets show the reduced magnetization $M\left(T\right)/M\left(0\right)$ vs $T^{3/2}$ in the low-temperature region. The straight lines are linear fit to the Bloch’s law.

Figure 5

(Color online) Temperature dependence of out-of-plane ZFC and FC magnetizations of (a) (110) and (c) (010) SRO films with their corresponding irreversibility magnetization $M_{\text{irr}}$ vs $T$ (b) (110) and (d) (010) SRO thin films.

Figure 6

(Color online) Field dependence of $T_g$ raised to the square and 2/3 powers for (a) (110) and (b) (010) SRO films. The solid lines are the fitted to data points with Eq. (2).

Figure 7

(Color online) Time relaxation of isothermal remanent magnetization $\left({\sigma }_{\text{IRM}}\right)$ and thermoremanent magnetization $\left({\sigma }_{\text{TRM}}\right)$ of SRO thin films. The “open circle” represents that for [110] films, while “solid circle” that for [010] films.

Figure 8

Schematic of field-temperature $\left(H\text{−}T\right)$ phase diagram of SRO thin films.