paper

Synthesis and physical properties of perovskite SmSrNiO (x = 0, 0.2) and infinite-layer SmSrNiO nickelates

arXiv:2010.11777 · doi:10.1088/1361-648X/abfb90

Abstract

Recently, superconductivity at about 9-15K was discovered in NdSrNiO infinite-layer thin films, which has stimulated enormous interests in related rare-earth nickelates. Usually, the first step to synthesize this 112 phase is to fabricate the RNiO phase, however, it was reported that the 113 phase is very difficult to be synthesized successfully due to the formation of unusual Ni oxidation state. And the difficulty of preparation is enhanced as the ionic radius of rare-earth element decreases. In this work, we report the synthesis and investigation on multiple physical properties of polycrystalline perovskites SmSrNiO (x = 0, 0.2) in which the ionic radius of Sm is smaller than that of Pr and Nd in related superconducting thin films. The structural and compositional analyses conducted by X-ray diffraction and energy dispersive X-ray spectrum reveal that the samples mainly contain the perovskite phase of SmSrNiO with small amount of NiO impurities. Magnetization and resistivity measurements indicate that the parent phase SmNiO undergoes a paramagnetic-antiferromagnetic transition at about 224K on a global insulating background. In contrast, the Sr-doped sample SmSrNiO shows a metallic behavior from 300K down to about 12K, while below 12K the resistivity exhibits a slight logarithmic increase. Meanwhile, from the magnetization curves, we can see that a possible spin-glass state occurs below 12K in SmSrNiO. Using a soft chemical reduction method, we also obtain the infinite-layer phase SmSrNiO with square NiO planes. The compound shows an insulating behavior which can be described by the three-dimensional variable-range-hopping model. And superconductivity is still absent in the polycrystalline SmSrNiO.

13 pages, 6 figures

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