  We propose a scheme to dynamically synthesize a space-periodic effective
magnetic field for neutral atoms by time-periodic magnetic field pulses. When
atomic spin adiabatically follows the direction of the effective magnetic
field, an adiabatic scalar potential together with a geometric vector potential
emerges for the atomic center-of-mass motion, due to the Berry phase effect.
While atoms hop between honeycomb lattice sites formed by the minima of the
adiabatic potential, complex Peierls phase factors in the hopping coefficients
are induced by the vector potential, which facilitate a topological Chern
insulator. With further tuning of external parameters, both a topological phase
transition and topological flat bands can be achieved, highlighting realistic
prospects for studying strongly correlated phenomena in this system. Our Letter
presents an alternative pathway towards creating and manipulating topological
states of ultracold atoms by magnetic fields.
