  We report an experimental study of the magnetic properties of infinite-layer
Nd1-xSrxNiO2 thin films by x-ray magnetic circular dichroism (XMCD) at Ni L3,2
and Nd M5,4 edges. We show that at low temperatures the out-of-plane component
of the Ni1+ spin-moment is characterized by a rapid increase for magnetic
fields below 1T , followed by a slower linear increase reaching a spin-moment
value of 0.25uB/Ni at 9T in the case of superconducting Nd0.8Sr0.2NiO2. On the
other hand, the Nd M5,4 XMCD shows a clear paramagnetic behaviour, which make
both Ni- and Nd-spin-sublattices fully uncorrelated.The magnetic field and
temperature dependencies of the Ni L3,2 XMCD data can be explained by assuming
an out-of-plane canting of the strongly in-plane anti-ferromagnetic ordered
Ni1+ spins. A symmetry lowering of the NiO2 planes observed via
four-dimensional scanning transmission electron microscopy, triggering a DMI,
can be responsible of the proposed Ni1+ spin-canting at zero-field. The
resulting out-of-plane weak-ferromagnetic coupling under magnetic field
explains the relatively large spin-moment and its magnetic field and
temperature dependence.
