The pressure dependence of the crystal structure of la₂cuo₄

Using energy dispersive diffraction techniques employing synchrotron radiation the authors measured the effect of pressure on the lattice parameters of La₂CuO₄. During compression the c/a ratio remains constant up to about 150 kbar showing that the effect of pressure is isotropic, in contrast with the magnetic properties which are highly two-dimensional. The results agree well with the predictions of band-structure calculations, suggesting that the bonding is governed by the La and O atoms and not by the Cu-O₂ layers.