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Description
We explore the synthesis and emergent electronic behavior of infinite-layer nickelate thin films (112 phase), focusing on Nd1-xEuₓNiO2 (NENO). The infinite layer superconducting phase is obtained from perovskite nickelates via a topotactic reduction, as demonstrated by D. Li [1] using CaH2 or NaH to selectively remove apical oxygens and induce a square planar NiO2 coordination. Following the solid-state route proposed by W. Wei [2,3], we deposit metallic aluminium onto a perovskite film and use the reaction 2Al + 3NdNiO3 → Al2O3 + 3NdNiO2 to obtain the 112 phase. All thin films were synthesized via RF off-axis magnetron sputtering, with the aluminum layer deposited in situ on-axis.
Using high-quality 113 nickelate films and heterostructures [4,5,6], the 112 NENO phase on LSAT and NdGaO3 (NGO) substrates respectively were successfully obtained. The interplay between the field response of the Eu²⁺ and Nd3+ magnetic ions and superconductivity in these infinite-layer systems was investigated.
The lower-Tc samples display a striking re-entrant superconducting behavior and distinct superconducting domes in the Hc2-Tc magnetic phase diagram are observed, consistent with the Jaccarino–Peter effect [7] linked to the negative exchange field between the magnetic rare earth ions and electron spins. The presented Hall effect data can be successfully modeled by including an anomalous Hall term proportional to the spin paramagnetic response of the aforementioned magnetic ions.
References:
[1] D. Li et al., Nature 572, 624-627 (2019)
[2] W. Wei et al., Physical Review Materials 7, 013802 (2023)
[3] W. Wei et al., Sci. Adv. 9, eadh3327 (2023)
[4] C. Domìnguez et al., Nat. Mater. 19, 1182–1187 (2020)
[5] L. Varbaro et al. APL Mater. 12, 081120 (2024)
[6] L. Varbaro et al., Adv. El. Mater. 9, 2201291 (2023)
[7] V. Jacca
