I was fired from my job as a registered medical practitioner by my manager two months back. He claimed in written termination letter that I had improperly handled/ documented/ controlled substances, which was a criminal offense). Though they failed to provide any valid evidence to support their claim, they maintained that I am ineligible for rehire in any other dept. of the hospital. I immediately got another employment and was denied a position after they contacted my previous manager for which I was completely eligible. Can I sue them for defamation?