Is it ok to ask professor to read my published article?
I think it is fine to send the article, but not even necessary to ask him/her to read it. It is enough just to make it available, with a note about where it is published. It will be read or not, whether you ask or not. It is also good whether it is closely related to the professors area of research or not.

But making it available easily is a good thing to do and should enhance the application. It shows something about your ability, even if the sub-field is different and even if it isn't read.