Synthesis, characterization and study of the magnetic properties of high-Tc superconducting cuprates

Full description

Cuprate unconventional superconductors hold the record for the highest superconducting transition temperatures reached so far, at ambient pressure. These compounds exhibit a complex electronic phase diagram dominated by a mysterious pseudogap phase that is thought to play a key role in the emergence of superconductivity. However, despite decades of research, the origin of this pseudogap phase remains an unsolved enigma. It encompasses electronic instabilities and, in particular, an exotic magnetic phase, interpreted as the signature of a magneto-electric quantum state so-called “loop currents” [1].

Recently, we discovered that these quantum states can lead to the formation of hidden magnetic textures that could play a crucial role in the pseudogap physics in the YBa2Cu3O6+x material, shedding light on another piece of the high-temperature superconductivity puzzle, and paving the way to new experimental investigations [2-3].

In order to probe the universality of these magnetic textures in the pseudogap phase, we target their study in another family of superconducting cuprates Bi2(La,Sr)2CuO6+x and as a function of the hole doping level in the YBa2Cu3O6+x and Bi2(La,Sr)2CuO6+x cuprate families. In this context, this internship project aims at the synthesis of these two families of cuprates, at different doping levels, in their polycrystalline form and their characterizations using X-ray diffraction and by means of magnetometry measurements. These powders will be used for the growth of single crystals of the same compositions by the floating zone method using a dedicated device; an image furnace. The project will also concern the characterization of the resulting single crystals by polarized light microscopy, X-ray diffraction, magnetic and specific heat measurements as well as chemical characterizations.

The internship project will be carried within the framework of a collaboration between the Laboratoire Léon Brillouin and Service de Physique de l’Etat Condensé (Saclay). It will take place in close collaboration with a PhD student currently carrying out her thesis project on this theme.
The recruited intern will be able to participate in one or more crystal growth experiments.
Polarized neutron diffraction experiments aiming at detecting the experimental signatures of the complex magnetic textures are also planned for spring 2025 on the high flux reactor at the Laue-Langevin Institute (in Grenoble).

The recruited intern will be able to participate to an experimental session.

• [1] Loop currents in quantum matter
  P. Bourges et al., 22,1, (2022)
  Philippe Bourges, Dalila Bounoua and Yvan Sidis, 22, C.R. Phys Special Issue S5 (2021), p. 7-31
• [2] Hidden magnetic texture in the pseudogap phase of high-Tc YBa2Cu3O6.6
  Dalila Bounoua, Yvan Sidis, Toshinao Loew, Frédéric Bourdarot, Martin Boehm, Paul Steffens, Lucile Mangin-Thro, Victor Balédent & Philippe Bourges, Communications Physics 5, Article number: 268 (2022)
• [3] Universality of 𝑞=/2 orbital magnetism in the pseudogap phase of the high-𝑇𝑐 superconductor YBa₂⁢Cu₃⁢O_6+𝑥 , Dalila Bounoua, Yvan Sidis, Martin Boehm, Paul Steffens, Toshinao Loew, Lin Shan Guo, Jun Qian, Xin Yao, and Philippe Bourges, Phys. Rev. B 108, 214408

Location

CEA-Saclay, (91) Essonne, France

Internship conditions

• Internship duration: 6 months
• Level of study: Bac+5
• Training: Master 2
• Continuation in PhD thesis: Yes
• Application deadline: February 1^st, 2025

Supervisor

Dalila Bounoua
Phone: 01 69 08 51 81
Email :