Hi, all. I'm wondering if anyone's done some simulation of magnetic material with LLG equation. The question is where can I find the value of exchange constant for a material. In LLG equation, the exchange constant is in the unit of "J/m", and the typical value is 10^-11 J/m, for some magnetic metal as far as I know. But I can't find a handbook or any online material summarizing this parameter for different materials. It seems complicated to derive based on the structure. Does anyone know where to look for such values? Thanks in advance.