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