the area seems to be "mature" in the sense that garbage collection theory/ dynamics is relatively well understood, surveys that come up in searches are years old and many state-of-the-art algorithms are now implemented, and maybe research in the area is far less common or active. also hardware assisted garbage collection seems an uncommon combination theoretically (also/ incl operating system aware/ crosscutting such as algorithms that intentionally mesh well by design with caches, paging, virtualization, etc). speaking as a practitioner in the field, garbage collection algorithms tuned with hardware features or OS mechanisms seems a promising idea that hasnt been explored much.
here is one survey turned up of 3 state of the art algorithms from 2013 and there is a hardware mechanism on the 1st (for reference counting).