  We study the phase structure and the microscopic interactions in regular
Bardeen AdS black hole. The stable and metastable phases in the black hole are
analysed through coexistence and spinodal curves. The solutions are obtained
numerically as the analytic solution to the coexistence curve is not feasible.
The $P_r-T_r$ coexistence equation is obtained using a fitting formula. The
coexistence and spinodal curves are plotted in $P_r-T_r$ and $T_r-V_r$ planes
to explore the phase structure of the black hole. In the second part of our
study, we were able to probe the microscopic interactions of regular Bardeen
AdS black hole using the novel Ruppeiner geometry proposed by S.W. Wei
\emph{et.al} Phys. Rev. Lett.123, 071103 (2019). It is found that the
microscopic interactions are not same in the small black hole (SBH) and large
black hole (LBH) phases. In the SBH phase, there exists a repulsive interaction
in the microstructure in the low temperature regime. In contrast, the
microstructure associated with the LBH phase has attractive interaction
throughout the parameter space. We found that, along the coexistence
temperature both the SBH and LBH branches diverge to negative infinity with a
critical exponent equal to $1/2$.
