{HEAD ~ the variable resistor} is formed of {TAIL ~ a metal oxide} showing an n type conductivity, and a work function of the second electrode is larger than a work function of the first electrode 
is formed of
{ HEAD ~ the variable resistor } is formed of { TAIL ~ a metal oxide } showing an n type conductivity , and a work function of the second electrode is larger than a work function of the first electrode
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH