Custody of my daughter if I die.

Is there some kind of document, other than a Will, that I can use to state that I want my mother to take custody of my daughter if I die? I'm a single mom and was never married to the father of my child. He abandoned us, and broke my car windshield on his way out. He abuses drugs and is violent and mentally abusive. I'm healthy, but my problem is that he could try to fight my mother for custody if something were to happen to me. What can I do? Can I just type my own letter and have it notarized? I am fearful of him deciding to come here and take her if I died and bringing her out of the state and over to the rest of his family which he openly admits is extremely abusive and dysfunctional and also abuse drugs and alcohol. We have no court agreements or anything. He calls to ask how "we're" doing once in a while and that's about it. He has sent small amounts of money here and there in the past ($50 give or take). My daughter is under a year old as well. He left when she was a month old, came back when she was about 3 months old and stayed for a week and left again. She is now 6 months old. I'm just looking for peace of mind.