  Evidence is mounting that charge order competes with superconductivity in
high Tc cuprates. Whether this has any relationship to the pairing mechanism is
unknown since neither the universality of the competition nor its microscopic
nature has been established. Here using nuclear magnetic resonance, we show
that, similar to La214, charge order in YBCO has maximum strength inside the
superconducting dome, at doping levels p = 0.11 - 0.12.We further show that the
overlap of halos of incipient charge order around vortex cores, similar to
those visualised in Bi2212, can explain the threshold magnetic field at which
long-range charge order emerges. These results reveal universal features of a
competition in which charge order and superconductivity appear as joint
instabilities of the same normal state, whose relative balance can be
field-tuned in the vortex state.
