Charge and Spin Order Dichotomy in NdNiO_{2} Driven by the Capping Layer.

Superconductivity in infinite-layer nickelates holds exciting analogies with that of cuprates, with similar structures and 3d-electron count. Using resonant inelastic x-ray scattering, we studied electronic and magnetic excitations and charge density correlations in Nd_{1-x}Sr_{x}NiO_{2} thin films with and without an SrTiO_{3} capping layer. We observe dispersing magnons only in the capped samples, progressively dampened at higher doping. We detect an elastic resonant scattering peak in the uncapped x=0 compound at wave vector (∼⅓,0), remindful of the charge order signal in hole doped cuprates. The peak weakens at x=0.05 and disappears in the superconducting x=0.20 film. The role of the capping on the electronic reconstruction far from the interface remains to be understood.

How to obtain a magnetic hard-soft architecture by pulsed laser deposition.

In spin valve type systems, one ferromagnetic electrode must be magnetically hard to act as a reference layer while the other electrode must be magnetically soft to act as a sensor or storage layer. This magnetic hard-soft architecture can usually be obtained by four different methods: the use of two ferromagnets with different coercive fields (here CoFe(2) and Ni(80)Fe(20)), the use of an underlayer enhancing the coercive field of one of the two ferromagnets (here Ta and Ru), the use of a ferromagnet coupled to a ferrimagnet or antiferromagnet (here NiO/CoFe(2) and CoFe(2)O(4)/CoFe(2)), or the use of an artificial antiferromagnet (here CoFe(2)/Ru/CoFe(2)). We show that at least the first and the third methods seem to work with pulsed laser deposition in the thermodynamic conditions used.