  Variable resistors were constructed from epitaxial SrRuO3 (SRO),
La0.67Sr0.33MnO3 (LSMO) and SrTiO3 layers with perovskite crystal structure.
Each layer was patterned separately by lithographic methods. Optimized wet
chemical etchants and several polishing steps in organic solvents allowed good
epitaxy of subsequent layers, comparable to epitaxy on pristine substrates.
Periodate as the oxidizing agent for SRO and iodide with ascorbic acid as the
reducing agents for LSMO were used to attack these chemically resistant oxides.
The final devices changed their conductance in a similar manner to previously
described variable resistors that were defined with shadow masks.
