Structurally-driven metal–insulator transition in Ca 2Ru 1− xCr xO 4 (0≤ x

Abstract

Correlation between structure and transport properties are investigated in high-quality single-crystals of Ca 2Ru 1− x Cr x O 4 with 0< x<0.14 using single crystal X-ray diffraction and by electronic studies. The parent compound was known to exhibit an intriguing first-order structurally driven metal–insulator (MI) transition at 357 K. Upon chromium doping on the ruthenium site, the metal–insulator transition temperature ( T MI) was drastically reduced, and is related to the competition between structural changes that occur upon Cr doping and with decreasing temperature. A strong suppression of structural distortions with increasing Cr substitution was identified. No clear T MI can be observed when x>13.5% and the system behaves as an insulator. Such a large, sharp metal–insulator transition and tuneable transition temperature may have potential applications in electronic devices.