索邦大学凝聚态物理方向招收博士生申请条件要求-申请方
主办方
索邦大学
PhD直招介绍
Title of the research project: Structure and elemental excitations in multiferoïc organic and metal-organic frameworks
Thesis supervisor:
Vita Ilakovac, Laboratoire de Chimie Physique - Matière et Rayonnement, Sorbonne University,Paris, France
Co-director:Pascale Foury-Leylekian, Laboratoire de Physique des Solides, Université Paris-Saclay, Orsay, France
Abstract
Even if the ferroelectricity and the magnetic order usually appear separately, there are rarecompounds, known as multiferroïcs, where the spin and the charge ordering coexist, andsometimes induce each other. The mechanism of their coexistence is one of major questions intoday’s materials science. In the case of large magnetoelectric coupling, important applications ofthese materials can be found in data storage domain, as they offer the possibility to controlferroelectric properties by magnetic fields and magnetism by electric fields. Moreover, they areimportant for the development of sustainable energy sources, like solar cells, as they offer thepossibility of efficient ferroelectric polarization-driven carrier separation.
The object of the proposed work is to reach a better understanding of the conditions which arenecessary to obtain a simultaneous appearance of the magnetic and the charge ordering. Thesystems we will be interested in are the organic charge-transfer salts, kappa-(BEDT-TTF)2X, andmetal-organic perovskite-like framework [(CH)3NH2]Fe(HCOO)3. We will study their detailedstructure and the elemental excitations, like dd-, charge transfer, or collective magnetic andphonon excitations. Two experimental techniques will mainly be used: diffraction (X-ray orneutron) and Resonant Inelastic X-ray Scattering (RIXS). The interpretation of the experimentaldata will be supported by ab-initio state-of-the-art electronic structure calculations andsimulations of the experimental spectra.
Subject description :
Even if the ferroelectricity and the magnetic order usually appear separately, there are rarecompounds, known as multiferroïcs, where the spin and the charge ordering coexist, and sometimesinduce each other. The mechanism of their coexistence is one of major questions in today’smaterials science. In the case of large magnetoelectric coupling, important applications of thesematerials can be found in data storage domain, as they offer the possibility to control ferroelectricproperties by magnetic fields and magnetism by electric fields. Moreover, they offer thepossibility of efficient ferroelectric polarization-driven carrier separation, important for solar energy conversion.
Bi-dimensional charge-transfer salts kappa-(BEDT-TTF)2X are model systems showing variousstates, depending on the counter-anion (X), and external parameters (pressure, temperature). Their structure is composed of layers of triangular constellation of dimers of BEDT-TTF (bis-(ethylene-thio)-tetra-thia-fulvalene) molecules, separated by anion layers parallel to the (b,c) plane. An extremely subtle competition between the spin frustration and the coulomb interactionresults in their different ground states. In particular, some of them are multiferroïc, others arequantum spin-liquids, showing no spin ordering despite a strong antiferromagnetic interaction.At the same time, most of them show some type of charge ordering.
On the other hand, in hybrid metal-organic frameworks with the AMX3 perovskite-likestructure the physical and chemical properties can be adjusted by varying components A and M.Besides potential applications in gas storage, catalysis, nonlinear optics, photoluminescence andsolar cells, some of them are multiferroïcs with intriguing magnetoelectric properties. Here we willbe particularly interested in the [(CH)3NH2]Fe(HCOO)3 system, where the metal Fe2+ cation linkedby formate groups (X = HCOO-) form the FeX2 skeleton and di-methyl-ammonium (DMA) cations(A = [(CH3)NH2]+) occupy the cavities, as it shows an intrinsic magnetoelectric effect at lowtemperature.
The object of the proposed work is to reach a better understanding of the conditions which arenecessary to obtain a simultaneous appearance of the magnetic and the charge ordering. For this, wewill study the detailed structure and the elemental excitations. Two experimental techniques willmainly be used: X-ray and neutron diffraction and Resonant Inelastic X-ray Scattering (RIXS). Theinterpretation of the experimental data will be supported by theoretical ab-initio state-of-the-artelectronic structure calculations.
Thesis limestones :
During the first year of the thesis the candidate will familiarize with RIXS and X-raydiffraction measurements and will be introduced to the way how to simulate the spectra. The goalwill be to complete the study of the element resolved excitations, electron-phonon coupling and thedetailed structure of the quantum spin-liquid kappa-(BEDT-TTF)2Ag2(CN)3 and multiferroïckappa-(BEDT-TTF)2Cu[N(CN)2]Cl salts. The second year will be dedicated to the study of thestructure and elemental excitations of the multiferroic organo-metallic hybride perovskite[(CH)3NH2]Fe(HCOO)3. The third year will be reserved for finishing all necessary experiments andsimulations and the redaction of the thesis manuscript.
索邦大学Phd申请条件和要求都有哪些？凝聚态物理方向招收博士生项目是不是全奖？有没有奖学金？下面我们一起看一下索邦大学申请Phd直招需要具备哪些条件和要求，以及托福、雅思语言成绩要到多少才能申请。
申请要求
Student with knowledge in chemical physics, material sciences or solid state physics. Good basis incrystallography and mater-light interaction is welcome.
报名方式
招生人信息
Vita Ilakovac
邮箱：vita.ilakovac-casses@upmc.fr
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