Hall-Higman type theorems for semisimple elements of finite classical   groups
  We prove an analogue of the celebrated Hall-Higman theorem, which gives a lower bound for the degree of the minimal polynomial of any semisimple element of prime power order $p^{a}$ of a finite classical group in any nontrivial irreducible cross characteristic representation. With a few explicit exceptions, this degree is at least $p^{a-1}(p-1)$. 
Pham Huu Tiep and Alexander E. Zalesskii