  We obtained Subaru FMOS observations of Halpha emitting galaxies selected
from the HiZELS narrow-band survey, to investigate the relationship between
stellar mass, metallicity and star-formation rate at z = 0.84 - 1.47, for
comparison with the Fundamental Metallicity Relation seen at low redshift. Our
findings demonstrate, for the first time with a homogeneously selected sample,
that a relationship exists for typical star-forming galaxies at z = 1 - 1.5 and
that it is surprisingly similar to that seen locally. Therefore, star-forming
galaxies at z = 1 - 1.5 are no less metal abundant than galaxies of similar
mass and star formation rate (SFR) at z = 0.1, contrary to claims from some
earlier studies. We conclude that the bulk of the metal enrichment for this
star-forming galaxy population takes place in the 4 Gyr before z = 1.5. We fit
a new mass-metallicity-SFR plane to our data which is consistent with other
high redshift studies. However, there is some evidence that the
mass-metallicity component of this high redshift plane is flattened, at all
SFR, compared with z = 0.1, suggesting that processes such as star-formation
driven winds, thought to remove enriched gas from low mass halos, are yet to
have as large an impact at this early epoch. The negative slope of the
SFR-metallicity relation from this new plane is consistent with the picture
that the elevation in the SFR of typical galaxies at z > 1 is fuelled by the
inflow of metal-poor gas and not major merging.
