PROBLEM TO BE SOLVED: To provide a point contact array wherein a plurality of point contacts are arrayed which electrically and reversibly control the conductance between electrodes while applicable to a calculation circuit, a logic circuit, a memory element, and the like.
SOLUTION: A plurality of point contacts are used which comprise a first electrode comprising a mixed conductor material 1 of ion conductivity and electron conductivity and second electrodes 3 and 4 comprising conductive material. The conductance of the point contact is controlled to constitute a circuit. Ag2S, Ag2Se, Cu2S, or Cu2Se is preferred as the mixed conductor material 1. If a conductor or an insulator material is inserted between the electrodes, the crystal body or amorphous body of GeSx, GeSex, GeTex, or WOx (0<x<100) is preferred as the semiconductor and the insulator material.