Lanthanum barium copper oxide, or LBCO, is an inorganic compound with the formula CuBa0.15La1.85O4.

[1] Johannes Georg Bednorz and K. Alex Müller shared the 1987 Nobel Prize in physics for the discovery that this material exhibits superconductivity at the then unusually high temperature.

In lanthanum barium copper oxide, some of the La(III) centers are replaced by Ba(II), which has a similar ionic radius.

This Ba-for-La replacement causes removal of some electrons (hole doping) from the d-band associated with the sheets of copper oxide.

[3] As a function of such chemical doping, the system changes its ground state from Mott insulating to superconducting.