  In this work, the microstructure of charged AdS black holes under minimal
length effects is investigated. We study the thermodynamics of black holes in
the extended phase space, where the cosmological constant is regarded as the
thermodynamic pressure. The modified Hawking temperature and phase transition
are obtained based on the generalized uncertainty principle (GUP). Then, using
thermodynamic geometry, we show that the microstructure of black holes can be
determined by the ratio of GUP parameter to charge. For a small ratio, the
black hole exhibits the typical RN-AdS microstructure with van der Waals phase
transition and repulsive/attractive interactions. As the ratio increases, the
reentrant phase transition takes place, and both the repulsion-attraction
coexisted black hole and the attraction dominated black hole can be found in
this case. For a large ratio, the black hole behaves like a Schwarzchild-AdS
black hole in which neither phase transition nor repulsive interaction exists.
These results suggest that the GUP effect will reduce the repulsive interaction
presented by the charged AdS black hole, which can also be qualitatively
understood from the perspective of black hole molecules.
