Let L = −∆ + V be a Schrödinger operator, where the potential V belongs to the reverse Hölder class. By the subordinative formula, we introduce the fractional heat semigroup {e −tL α } t>0 , α > 0, associated with L. By the aid of the fundamental solution of the heat equation:we estimate the gradient and the time-fractional derivatives of the fractional heat kernel K L α,t (•, •), respectively. This method is independent of the Fourier transform, and can be applied to the second order differential operators whose heat kernels satisfying Gaussian upper bounds. As an application, we establish a Carleson measure characterization of the Campanato type space BMO γ L (R n ) via {e −tL α } t>0 .