It has now become possible to fabricate high quality oxide “heterostructures”: multilayer systems in which one or more unit cell thick films of one material with interesting electronic properties (such as a colossal magnetoresistance manganite) are interleaved with one or more unit cell thick films of another, with essentially perfect epitaxy [1]. This talk will summarize the present status of the field, including challenges and implications. Recent progress [2,3] in theoretical analysis of (001) ($A_n A’_m BO_3$) heterostructures will be summarized, including studies of “colossal” magnetoresistance manganite and Mott/insulator band insulator systems will be presented, and placed in the context of the general theory [4] of behavior of surface and interface phenomena in correlated electron materials. Strengths and weaknesses of presently available theoretical techniques will be outlined. The crucial importance of characterizing the charge profile will be demonstrated.

[1] A. Ohtomo, D.A. Muller, J.L. Grazul, and H.Y. Hwang, Nature (London) 419, 378 (2002).
[2] Satoshi Okamoto and A.J. Millis, Phys. Rev. B70 195120/1-5 (2004) and cond-mat/0601081.
[3] C. Lin and A.J. Millis, cond-mat/0512061.
[4] A.J. Millis, in “Oxide Thin Films and Heterostructures”, S. Ogale, ed. Springer Verlag, in press.

Columbia University