Is it possible to define a variable and using a superscribt in the variable name?

Another question: Is it possible to define a variable with using a subcribt of 2 thetas besides each other?

if i write sigma[rr]:= it has no problem, but if i write sigma[thetatheta] then it only writes thetatheta as the subscribt and not the 2 symbols besides each other. Is there a way to fix this?

see picture for clarification: