  In this paper, we have investigated the effect of magnetic field numerically
as well as analytically for holographic insulator/superconductor phase
transition in higher dimensional Gauss-Bonnet gravity. First we have analysed
the critical phenomena with magnetic field using two different numerical
methods, namely, quasinormal modes method and the shooting method. Then we have
carried out our calculation analytically using the St$\ddot{u}$rm-Liouville
eigenvalue method. The methods show that marginally stable modes emerge at
critical values of the chemical potential and the magnetic field satisfying the
relation $\Lambda^2\equiv\mu^2-B$. We observe that the value of the chemical
potential and hence the value of $\Lambda$ increases with higher values of the
Gauss-Bonnet parameter and dimension of spacetime for a fixed mass of the
scalar field. This clearly indicates that the phase transition from insulator
to superconductor becomes difficult in the presence of the magnetic field for
higher values of the Gauss-Bonnet parameter and dimension of spacetime. Our
analytic results are in very good agreement with our numerical results.
