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Sujet de stage / Master 2 Internship

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Nickelates: a new superconducting oxide family

Contact: Moussy J.-B./Colson Dorothee, , jean-baptiste.moussy@cea.fr / dorothee.colson@cea.fr , +33 1 69 08 72 17/ 73 14
Summary:
We propose you to synthesize and study the structural and physical properties of thin films of the new infinite layer superconductor, nickelate Nd0.8Sr0.2NiO2 [1]. The discovery of this superconducting phase (at about 10-15 K) should allow progress to be made in understanding the mechanisms involved in high temperature superconductors.
[1] D. Li et al. Nature. 572, 624 (2019)
Possibility of continuation in PhD: Oui
Deadline for application:30/04/2020

Full description:
Scientific description:
The discovery of high-Tc superconductivity in cuprates [1] has motivated the study of oxides with similar crystalline and electronic structure with the aim of finding additional superconductors and understanding the origins of this unconventional superconductivity. Isostructural examples include the superconducting Sr2RuO4 ruthenate or the electron-doped Sr2IrO4 iridate even if a zero-resistance state has not yet been observed in this last compound [2]. Recently, the superconductivity in the infinite layer Nd0.8Sr0.2NiO2 nickelate [3] has also been observed by using a soft-chemistry topotactic reduction of the perovskite precursor phase. The discovery of this superconducting phase (around 10-15 K) should allow to progress in the understanding of the mechanisms involved in high-Tc superconductors.
During this internship, the student will perform the crystalline growth of pure and (Nd/Sr) substituted NdNiO3(001) thin films on single-crystal SrTiO3(001) substrates by pulsed laser deposition (PLD). Once grown, the student will test reducing treatments allowing the formation of the expected infinite layer phase. A peculiar attention will be given to the structural and physical properties of oxide thin films by using in situ electron diffraction (RHEED), photoemission spectroscopy (XPS/UPS) or ex situ techniques such as near-field microspcopy (AFM), magnetism (SQUID, VSM). The electronic properties of samples will then be studied as a function of temperature (resistivity, Hall coefficient, current-voltage characteristics) in order to analyze the superconducting behavior.

[1] J. G. Bednorz and K. A. Müller, Z. Phys. B 64, 189 (1986).
[2] Y.J. Yan et al., Phys. Rev. X. 5, 041018 (2015).
[3] D. Li et al. Nature. 572, 624 (2019).
Technics/methods used during the internship:
Thin films will be deposited by pulsed laser ablation (PLD). Structural and physical properties will be studied by in situ electron diffraction (RHEED), photo-emission spectroscopy (XPS/UPS) or ex situ techniques such as near field microspcopy (AFM), magnetism (SQUID, VSM). The electronic properties of the samples will be studied as a function of temperature (resistivity, Hall coefficient, current - voltage characteristics) in order to analyze the superconducting behaviour.

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