Switching device and resistance variable device

A switching device, comprising:

• a first electrode;
• a second electrode;
• and a switching layer disposed between the first electrode and the second electrode, wherein
• the switching layer contains a material containing a first cation element Z, tellurium, and nitrogen, wherein
• the material contains 5 atomic % or more of each of the first cation element Z, tellurium, and nitrogen, and
• when an atomic ratio of tellurium is X, an atomic ratio of nitrogen is Y, an atomic ratio of the first cation element Z is W, a ratio of Z2Te3 to ZN on a straight line connecting a compound of the first cation element Z with tellurium and nitride of the first cation element Z in a ternary phase diagram of the first cation element Z, tellurium, and nitrogen is A, and a change amount in the atomic ratio of nitrogen from the straight line connecting Z2Te3 and ZN in the ternary phase diagram is B, the material has a composition satisfying:
• X=1.2(1−A)(0.5+B) General equation 1:
• Y=A(0.5+B) General equation 2:
• W=1−X−Y General equation 3:
• where −0.06≤B≤0.06 is satisfied when ⅓>A and ¾<A, and −0.06≤B and Y≤0.45 are satisfied when ⅓≤A≤¾.