Investigation of the antiferromagnetic order in superconducting nickelates

Recently, superconductivity has been surprisingly reported at 15 K in Sr-doped NdNiO2 suggesting the existence of a new family of high-temperature superconductors. The structure of this nickel oxide consists in a stacking of NiO2 layers separated by rare-earth spacer layer, stabilizing the unusual Ni1+ oxidation state, corresponding to 3d9 electronic configuration, similarly to the cuprates. Our previous experiment on WISH @ ISIS, brought evidence for a AF order with a propagation vector of q_AF=(1/2,1/2,0), in two samples, a pure and 5% Sr-doped (Nd,Sr)NiO2 that could be at the origin of magnetic fluctuations playing a key role in the emergence of superconductivity. We first proposed to establish if this magnetic order is related to Nd or Ni atoms by studying LaNiO2 analogue. Then we proposed to precisely study the temperature dependence of the magnetic order and its possible connection to the low temperature upturn reported in resistivity in the (Nd1-xSrx)NiO2 with x=0,0.05.
WISH beamline is perfectly suited for magnetic structure determination and temperature evolution study. The study will be done at five chosen temperatures in the range 1-100K for the three samples, (Nd1-xSrx)NiO2 with x=0,0.05 and LaNiO2. Based on the previous experiment characteristics, we expect to count 4h per temperature. We thus ask for 3 days on the WISH high-resolution cold-neutron powder diffractometer to carry out our investigations