  Using a recently proposed Ginzburg-Landau-like lattice free energy functional
due to Banerjee et al. Phys. Rev. B 83, 024510 (2011) we calculate the
fluctuation diamagnetism of high-Tc superconductors as a function of doping,
magnetic field and temperature. We analyse the pairing fluctuations above the
superconducting transition temperature in the cuprates, ranging from the strong
phase fluctuation dominated underdoped limit to the more conventional amplitude
fluctuation dominated overdoped regime. We show that a model where the pairing
scale increases and the superfluid density decreases with underdoping produces
features of the observed magnetization in the pseudogap region, in good
qualitative and reasonable quantitative agreement with the experimental data.
In particular, we explicitly show that even when the pseudogap has a pairing
origin the magnetization actually tracks the superconducting dome instead of
the pseudogap temperature, as seen in experiment. We discuss the doping
dependence of the `onset' temperature for fluctuation diamagnetism and comment
on the role of vortex core-energy in our model.
