Possibly and the co-workers may have liability too. Slander is not a violation of public policy -- it is simply a legal wrong. But too many other issues: if there' an HR department of any kind there is probably some kind of disciplinary process so without knowing all of those things it's impossible to say. You should see an attorney who can determine what your work place situation was and whether any company policies were in place and/or not followed -- those "modify" the "at will" doctrine.
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