Theoretical simulations show the presence of persisting, global g-modes oscillations in early A-type stars, outside the border of the classical instability strip and SPB instability strip. We are conducting a spectroscopic survey in order to detect the presence of these modes, which would be very useful tools to study the convective cores of the stars. From the spectra observed and analyzed so far, we found evident line profile variations in one object (HR6139), which can be explained by the presence of prograde nonradial g modes. This behaviour can be explained by the presence of a local iron enhancement region, which leads to the appearence of an iron convection zone.