Local matrix-cluster interactions in a phase separated perovskite

Magnetoelectronic phase separation plays an integral part in many recent advances in the understanding of correlated electron systems. We have studied the magnetically phase separated material ${\mathrm{La}}_{1-x}{\mathrm{Sr}}_x\mathrm{Co}{\mathrm{O}}_3$ and observe unambiguous evidence of magnetic interactions between hole-rich ferromagnetic clusters and the neighboring hole poor matrix. We suggest that this mechanism detected here plays an important role in the rich electrical and magnetic properties of ${\mathrm{La}}_{1-x}{\mathrm{Sr}}_x\mathrm{Co}{\mathrm{O}}_3$.

Figure 1

(Color online) The field dependent depolarization rates as a function of reciprocal temperature $(>50\mathrm{K})$ for $\mathrm{La}\mathrm{Co}{\mathrm{O}}_{3-\delta }$, Arrhenius fits to the data along with the respective fitting components are also shown as described in the text. The inset shows the entire temperature range studied of ${\lambda }_{tf}^s$.

Figure 2

(Color online) Field cooling dependence of the natural logarithm of the remnant magnetization for $\mathrm{La}\mathrm{Co}{\mathrm{O}}_{3-\delta }$ (Ref. 11), as an inverse function of magnetic field, $T=50\mathrm{K}$. The inset shows the temperature dependence of the remnant moment after cooling in a field of $50\mathrm{m}\mathrm{T}$ until the appropriate temperature and then measuring in the remnant field.

Figure 3

(Color online) Temperature dependence of the initial asymmetry $\left(A_{tf}^s\right)$ of the oscillatory component for the $x=0.03$ sample directly compared to the differential of the FC mass susceptibility. The inset demonstrates the temperature dependent reciprocal mass susceptibility with respect to the measuring field.

Figure 4

(Color online) Temperature dependence of the depolarization rates for the $x=0.03$ sample obtained from the oscillatory component in equation (1). The inset shows the inverse temperature dependence of the depolarization rate above $30\mathrm{K}$.

Figure 5

(a) Temperature dependent comparison of the susceptibility (squares) and initial asymmetry (triangles) of the $x=0.15$ (filled) and 0.20 (hollow) samples. (b) The temperature dependence of the depolarization rates $\left(\lambda \right)$ for the two samples.