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