Australian Yorkshire Terrier
What Is A Mix Breed Of Australian Terrier And A Yorkshire Terrier Called?
A mixed breed dog--not a registrable pet or show dog
I am not sure that the breeding of an Australian Shepherd and a Yorkshire terrier has picked up enough in popularity to garner its own breed name such as the labradoodle which is a popular mix which is made between a lab and a poodle.
I believe the term you're looking for is, "mutt".