Dernière mise à jour : 24-11-2017

3 sujets /PHELIQS/GT

 

Theoretical study of advanced magnetocaloric materials

SL-DRF-18-0177

Research field : Solid state physics, surfaces and interfaces
Location :

Photonique, Electronique et Ingénierie Quantiques (PHELIQS)

Groupe Théorie (GT)

Grenoble

Contact :

MIKE ZHITOMIRSKY

Starting date : 01-10-2018

Contact :

MIKE ZHITOMIRSKY

CEA - DRF/INAC/PHELIQS/GT

04.38.78.43.30

Thesis supervisor :

MIKE ZHITOMIRSKY

CEA - DRF/INAC/PHELIQS/GT

04.38.78.43.30

Laboratory link : http://inac.cea.fr/Phocea/Vie_des_labos/Ast/ast_groupe.php?id_groupe=1157

An external magnetic field affects the entropy of a magnetic system and provokes temperature variations which can be used for magnetic refrigeration. Such an alternative cooling technology is increasingly important nowadays for space telescopes, particle physics experiments and quantum computing. The existing adiabatic demagnetization refrigerators utilize paramagnetic salts, which have limited capacity for temperatures above 1 K. Recently, two new families of magnetocaloric materials suitable for applications in the 1-4 K temperature range have been proposed: geometrically frustrated spin systems and dipolar magnets. We plan to study the magnetocaloric properties of such materials using large scale Monte Carlo simulations of realistic spin models appropriate for the known, Gd3Ga5O12 and GdLiF4, as well as for the prospective, Yb2Ti2O7 and Yb3Ga5O12, magnetocaloric materials. The theoretical study will benefit from a collaboration with the on-going experimental work at INAC.

Quantum transport in voltage-biased topological Josephson junctions

SL-DRF-18-0281

Research field : Theoretical Physics
Location :

Photonique, Electronique et Ingénierie Quantiques (PHELIQS)

Groupe Théorie (GT)

Grenoble

Contact :

Manuel HOUZET

Julia MEYER

Starting date : 01-10-2018

Contact :

Manuel HOUZET

CEA - DRF/INAC/PHELIQS/GT

04.38.78.90.44

Thesis supervisor :

Julia MEYER

Université Grenoble Alpes - DRF/INAC/PHELIQS/GT

04.38.78.31.46

Personal web page : http://inac.cea.fr/Pisp/julia.meyer/

Laboratory link : http://inac.cea.fr/en/Phocea/Vie_des_labos/Ast/ast_groupe.php?id_groupe=501

Topological phases of matter have attracted much interest in recent years. Topological superconductors are of particular interest because they may host Majorana bound states [1]. Josephson junctions have been proposed as probes of topological superconductivity, and possible signatures of such Majorana bound states in topological Josephson junctions have indeed been observed [2,3,4]. However, important aspects related to the effect of the environment on the properties of the junction are still not fully understood. The aim of the thesis is to make progress in the understanding of quantum transport in voltage-biased topological Josephson junctions in the presence of an electromagnetic environment.

Interaction effects on topological properties of multiterminal Josephson junctions

SL-DRF-18-0289

Research field : Theoretical Physics
Location :

Photonique, Electronique et Ingénierie Quantiques (PHELIQS)

Groupe Théorie (GT)

Grenoble

Contact :

Julia MEYER

Manuel HOUZET

Starting date : 01-10-2018

Contact :

Julia MEYER

Université Grenoble Alpes - DRF/INAC/PHELIQS/GT

04.38.78.31.46

Thesis supervisor :

Manuel HOUZET

CEA - DRF/INAC/PHELIQS/GT

04.38.78.90.44

Personal web page : http://inac.cea.fr/Pisp/manuel.houzet/

Laboratory link : http://inac.cea.fr/en/Phocea/Vie_des_labos/Ast/ast_groupe.php?id_groupe=501

There is currently an active search for new phases of matter that admit topologically protected edge states. A promising route to realize them consists in combining conventional materials into appropriate heterostructures. Multiterminal Josephson junctions between conventional superconductors may be considered as topological materials themselves. As an example, 4-terminal junctions can accommodate topologically protected zero-energy bound states, which form so-called Weyl singularities. Their existence may be revealed through a quantized transconductance, like in the quantum Hall effect, but without magnetic field. The aim of the project will be to explore further this recent idea by investigating theoretically the robustness of this prediction in the presence of local Coulomb repulsion within the junction. In particular, the fate of Weyl singularities will be analyzed within an actual quantum-dot model for the junction.

• Solid state physics, surfaces and interfaces

• Theoretical Physics

 

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