Magneto-transport of filling controlled Mott insulator, Sr$_2$IrO$_4$

Sr$_2$IrO$_4$ (SIO) is shown to be a special Mott insulator with the ground state stabilized by a combination of electron correlation and spin-orbit coupling. [1] Both structurally and electronically, electron doped SIO shows characteristics comparable to hole doped La$_2$CuO$_4$, one of the parent compounds of the high-T$_{\mathrm{c}}$ cuprates. [2] This leads us to a natural question of whether doped SIO can turn into a metal and eventually a superconductor. Sustained efforts of chemically doping SIO, [3] without altering its band structure significantly, have been severely hampered due to solubility limitations. In this work, we perform a combination of chemical and electrostatic doping of SIO, to explore the possibility of achieving a robust metallic state. We show that undoped SIO shows ambipolar characteristics and there is significant gating action even after heavy alloying of SIO with La. In depth magneto-transport measurements such as Hall effect and magnetoresistance also provide us a deeper understanding of electronic structure and transport in this exotic Mott insulator. \\[4pt] [1] B. J. Kim et. al., PRL (2008).\\[0pt] [2] F. Wang and T. Senthil, PRL (2011).\\[0pt] [3] Y. Klein and I. Terasaki, J. Phys. : CM (2008).