The steady magnetohydrodynamic boundary-layer flow of a conducting ferro-nanofluid over a permeable stretching sheet of variable thickness subject to Hall effect, thermal radiation, viscous dissipation, Brownian diffusion, thermophoresis and first order chemical reaction is analyzed. A uniform transverse magnetic field along with the consideration of the Hall effect produces an additional secondary fluid motion in association with the main stretching flow. Applying the similarity transformation technique, the governing equations of conservation of mass, momentum, energy and species concentrations are transformed into a nonlinear system of ordinary differential equations. The numerical solution of the similarity equation with proper boundary conditions is obtained using a fourth order Runge-Kutta shooting algorithm under appropriate convergence criteria. It is found that a higher magnetic parameter decreases the main flow velocity and increases the secondary velocity due to Hall effect. Thermal boundary layer thickness increases with increasing Brownian motion and thermophoresis but decreases with increasing chemical reaction rate and Lewis number. The wall gradient profiles reveal that an increase in the interaction between magnetic field and flow leads to enhance the magnitude of the primary shear as well as significantly changes the heat and mass transfer.
