We report the fabrication and measurements of ionic liquid gated Hall bar devices prepared on the ab face of a thin Ca3Ru207 flake exfoliated from bulk single crystals that were grown by a floating zone method. The devices were categorized into two types: Those with their electrical transport properties dominated by r-axis transport in type A or that of the in-plane in type B devices. Bulk physical phenomena, including a magnetic transition near 56 K, a structural and metal-insulator transition at a slightly lower temperature, as well as the emergence of a highly unusual metallic state as the temperature is further lowered, were found in both types of devices. However, the Shubnikov-de Haas oscillations were found in type A but not type B devices, most likely due to enhanced disorder on the flake surface. Finally, the ionic liquid gating of a type B device revealed a shift in critical temperature of the structural and metal-insulator transition, suggesting that this transition is tunable by the electric field effect.
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We would like to thank M. Sigrist, N. Staley, and M. Ulrich for useful discussions. Work at Penn State was carried out primarily with the support of DOE under Grant No. DE-FG02-04ER46159. The sample fabrication was carried out at Penn State MRI Nanofabrication Lab under NSF Cooperative Agreement No. 0335765, NNIN with Cornell University. The work at Tulane was supported by the NSF under Grant No. DMR-1205469. Y.L. also acknowledges support from the National Science Foundation (NSF) under Grant No. DMR 0908700 and MOST of China (Grant No. 20I2CB927403) and NSFC (Grant No. 11274229) for data analysis and manuscript preparation.