  The quest for unconventional superconductivity governed by Coulomb repulsion
between electrons rather than phonon attraction received new momentum with the
advent of moir\'e graphene. Initially, delineating the phonon and
Coulomb-repulsion-based pairing mechanisms has proven to be a challenging task,
however the situation has changed after recent discovery of superconductivity
in non-twisted graphene bilayers and trilayers. Superconductivity occurring at
the phase boundaries of spin and valley polarized orders calls for non-phonon
scenarios, yet the specific pairing mechanisms remain to be understood. Here we
analyze a striking example -- superconductivity in graphene bilayers occurring
at the onset of valley-polarized order induced by a magnetic field. We describe
an attraction-from-repulsion mechanism for pairing mediated by a
quantum-critical mode, which fully explains the observed phenomenology. While
it is usually notoriously difficult to infer the pairing mechanism from the
observed superconducting phases, this case presents a rare exception, allowing
for a fairly unambiguous identification of the origin of the pairing glue. A
combination of factors such as the location of superconducting phase at the
onset of isospin-polarized phase, a threshold in a magnetic field, above which
superconductivity occurs, and its resilience at high magnetic fields paints a
clear picture of a triplet superconductivity driven by quantum-critical
fluctuations.
