Anomalous Electronic State in ${\mathrm{CaCrO}}_3$ and ${\mathrm{SrCrO}}_3$

Comprehensive measurements of electrical transport properties under pressure, thermal conductivity, magnetic susceptibility, and room-temperature compressibility have been used to characterize ${\mathrm{SrCrO}}_3$ and ${\mathrm{CaCrO}}_3$ perovskites synthesized under high pressure. Comparison with other narrow-band perovskite oxides suggests that their anomalous physical properties are correlated with bond-length instabilities caused by the crossover from localized to itinerant electronic behavior.

Figure 1

X-ray powder diffraction pattern for ${\mathrm{SrCrO}}_3$ and ${\mathrm{CaCrO}}_3$ with Cu $K\alpha$ radiation. Fitting patterns from the Rietveld analysis are also superimposed in the figure. Results from the Rietveld analysis are listed inside the figure.

Figure 2

Temperature dependences of the magnetization, resistivity, thermoelectric power, and thermal conductivity of ${\mathrm{SrCrO}}_3$, ${\mathrm{LaNiO}}_3$, and ${\mathrm{LaCuO}}_3$.

Figure 3

The same as Fig. 2 (without resistivity) for ${\mathrm{CaCrO}}_3$. Inset: magnetization to 5.5 T at 5 K.

Figure 4

Pressure dependence of the volume for ${\mathrm{SrCrO}}_3$ and ${\mathrm{CaCrO}}_3$. Inset: the pressure dependence of the Cr-O bond length for ${\mathrm{SrCrO}}_3$; see the text for details.

Figure 5

Pressure dependence of the resistance at 280 K. Inset (a) temperature dependence of the renormalized resistance at different pressures; inset (b) pressure dependence of the metal-insulator transition temperature.