When considering a hammer, you need to find out if the one you want is pneumatic or hydraulic. Once you know the type, find the spec on what it takes as far as pressure, CFM, or GPM hydraulic flow. Then you are ready to search for a tractor with matching specifications. If you buy the tractor first, you will probably find it is underpowered. Skid steer loaders do come with much higher flow rates on their hydraulic systems. They are like the Swiss Army Knife of equipment.
BTW: If you are talking about the traditional hand-held jackhammer (60-lb or 90-lb), most all of these are pneumatic and require a commercial high-flow air compressor of around 90 CFM. There are small demolition hammers that are electrical and can be rented or purchased for around $500.