http://www.redsweaters.org/RedSweaters.html
I knit some Barbie-size sweaters for the above organization - but I'm not sure if any of the patterns given are as detailed as you want so they could be learning tools, but will certainly work if you just want tree ornaments.
Did you try googling 'Barbie Doll Knit Patterns" or similar. It will give you lots of sites & patterns to look at.
If you can't find a raglan sweater for Barbie, maybe switch to a bigger doll - it might be easier to find the detail needed in a larger size.