How does one specify a particular letter to be serif in the beamer class? I want to keep the notation as similar in the presentation as the article as I can, and most of it turns out well, except for the capital Greek letter phi. I found this question to achieve my goal (the letter looks like I want it to look, but the feel of the presentation has altered due to the serif font in math mode). As a result, I'm just trying to change the single letter.
If necessary, I can add a MWE, but it doesn't seem necessary to me at the moment.