The surface layer of cleaved bilayer manganites

Recently, several informative reports have been published on spectroscopy experiments performed on cleaved surfaces of the bi-layered CMR manganite La2¡2xSr1+2xMn2O7 (LSMO) [1, 2, 3, 4]. For the detailed interpretation of these results, it is of importance to know exactly which layer within the crystal structure is exposed to the surface upon cleavage. Here we combine crystal structure arguments, scanning tunneling microscopy and XPS measurements to demonstrate that the crystals cleave between the rare-earth rock-salt oxide layers, leaving one outermost rare-earth oxide layer before the first electronically active MnO bilayer.