pressure effect; slow magnetic relaxation; n/a; graphene oxide; mixed metal Co/Ln clusters; X-ray diffraction; magnetism; AC susceptibility; two-dimensional (2D) ferrimagnets; cobalt; coordination clusters; lanthanides; DFT calculation; long-range magnetic ordering; iron complex; single-molecule magnets; lanthanide complex; coordination polymers; octacyanidoniobate(IV); ferromagnetism; nickel(I…