MBE growth and properties of T′-La2CuO4 thin films

We prepared thin films of T′-La2CuO4, which usually crystallizes in the T structure, by MBE, and investigated their properties while systematically changing the post-reduction conditions with a view towards obtaining superconductivity along the lines of the parent compound superconductors we have recently reported (O. Matsumoto et al., Phys. Rev. B 79 (2009) 100508(R)). The results indicate that the optimal reduction window is very narrow, near which metallic conductivity is obtained down to 50 K. The resistivity of the T′-La2CuO4 films is in the range of 10−2–10−3 Ω cm, which is several orders of magnitude lower than that of the counterpart T-La2CuO4, the implication of which is briefly discussed from the viewpoint of the difference in electronic structure induced by different oxygen coordination.