  We present an experimental study of the pyrochlore coumpound Nd2Zr2O7 by
means of neutron scattering and magnetization measurements down to 90 mK. The
Nd$^{3+}$ magnetic moments exhibit a strong local $\langle$111$\rangle$ Ising
anisotropy together with a dipolar-octupolar nature, different from the
standard Kramers-doublet studied so far. We show that, despite the positive
Curie-Weiss temperature, \ndzr\ undergoes a transition around 285 mK towards an
all-in$-$all-out antiferromagnetic state. We establish the $(H,T)$ phase
diagram in the three directions of the applied field and reveal a metamagnetic
transition around 0.1 T. The strongly reduced ordered magnetic moment as well
as the unexpected shape of the magnetization curves demonstrate that Nd2Zr2O7 ,
is not a standard Ising antiferromagnet. We propose that the peculiar nature of
the Nd doublet combined with competing interactions explain these findings.
