Electrical and magnetic properties of Na doped Ca$_{\mathrm{2}}$IrO$_{\mathrm{4}}$

The coexistence of strong spin-orbit coupling and electron correlation in layered iridates can lead to the interesting J$_{\mathrm{eff}}=$1/2 Mott state, which has been studied in perovskite-like Sr$_{\mathrm{2}}$IrO$_{\mathrm{4}}$ and Ba$_{\mathrm{2}}$IrO$_{\mathrm{4}}$. Unlike its sister compound, the bulk Ca$_{\mathrm{2}}$IrO$_{\mathrm{4\thinspace }}$exhibits hexagonal structure, while the Ruddlesden-Popper phase tetragonal structure$_{\mathrm{\thinspace }}$is thermodynamically unstable. Bulk Ca$_{\mathrm{2}}$IrO$_{\mathrm{4\thinspace }}$has semiconducting behavior, and the spin 1/2 Ir$^{\mathrm{4+}}$ ions carry magnetic moments. Doping Na creates electron deficiency in Ca$_{\mathrm{2}}$IrO$_{\mathrm{4}}$. In this talk, I will discuss electrical and magnetic measurements on newly synthesized Na doped Ca$_{\mathrm{2}}$IrO$_{\mathrm{4}}$. Experimental results on single crystal Ca$_{\mathrm{2}}$IrO$_{\mathrm{4}}$ will also be discussed.