Have I been defamed?

APRN at an academic medical center. I have had some issues with work flow in my unit and I complained about it to the manager several times with no help. One employee falsely told a manager that I called another employee (who I have only ever had one interaction with) a name behind his back. The manager, (who I complained about earlier this year) disclosed this to him and then wrote an incident report to human resources that it was reported to her I had called an employee this name. The other employee (who did not ask me about it) told human resources that this made him uncomfortable working with me. I am under investigation pending the written statements of the employee who reported it. I denied it and expressed my dissatisfaction with the process. I feel my reputation has been harmed over a false allegation. Am I correct to believe I have been defamed?