Two PhD positions in fabrication and computational design of stacking of oxide freestanding membranes into artificial heterostructures - DTU Energy

Updated: 5 months ago

There are two available PhD fellowships in the Department of Energy Conversion and Storage, Technical University of Denmark, to work on a project to design and fabricate a stack of artificial freestanding oxide membranes where the interface can be tuned by the choice of the membrane's material and orientation.  

Our team of experts has developed an innovative approach to creating free-standing ultra-thin oxide membranes. These membranes have a wide range of potential applications in fields such as electronics and energy. Our freestanding oxide membrane technology allows us to create membranes that are just a few atoms thick yet still maintain their structural integrity. The PhD research programme is part of the ERC Advanced project NEXUS and is dedicated to pushing the boundaries of what is possible with oxide membrane technology. The approach of NEXUS is radically different from past work and will provide fundamental breakthroughs in the study of transport across interfaces, and we are excited to bring our expertise to your project. 

Research project
The overall objective of the project is to assemble ultrathin freestanding oxide membranes into 3D artificial heterointerfaces and to provide a fundamental understanding of how to engineer the structure and the ionic transport across and along these interfaces.

Complex transition-metal oxides (TMOs) thin film - inorganic crystals containing oxygen and at least two other elements - exhibit one of the most common materials used in electronics and energy related technologies. Traditionally, these complex oxides are grown epitaxially with a well-regulated growth scheme and atomic level control over the material interfaces and substrate surfaces thereby these epitaxial films are clamped by the substrate. Recently, new methods have been developed, bridging the realms of epitaxial complex oxides and of low-dimensional VdW materials systems. In NEXUS we seek to take a leap from our present knowledge by creating artificial oxide heterostructures by directly stacking freestanding membranes with different crystal structures and orientations.

The current PhD research programme will look at investigating these novel oxide heterostructrures for finding new types of ionic conduction in the artificial interfaces.
The overall aim of this project is to:

  • fabricate, stack and twist artificial freestanding oxide membranes where the interface will be tuned by choice of the membranes’ material and orientation.
  • engineer the fastest path for transport using external stimuli, e.g. light, strain and temperature.
  • explore and understand the emergent ionic and electronic conduction in these artificial interfaces, determining the physical and chemical origin of interfacial conduction.
  • provide theoretical insight to unveil the interfacial reconstruction and stability of the artificial heterostructures as well as chemical bonds which can be restored at desired locations when non-epitaxial membranes re-assemble.
  • PhD 1: Theoretical modelling and simulations

    Responsibilities and qualifications
    The successful candidate will combine Density Functional Theory (DFT) with Machine Learning (ML)approaches to study the Moiré patterns, reconstructions, and formation of defects generated by the mismatch between the two interfacial oxides. The candidate will design an automatic computational workflow capable of generating a DFT data training set by itself without human intervention. The DFT data will be generated at the hybrid level to ensure a high accuracy level. These DFT simulations will use global minimum search algorithms to capture local reconstructions. We will use this data to train a ML force field using generalized neural networks. The ML force field will be able to work with Moiré patterns up to 100.000 atoms with the same precision as DFT, enabling the modelling of long-range reconstructions, which could eventually have a large impact on ionic transport.

    Candidates should be highly motivated and must hold a master's degree (or equivalent), preferably in a related discipline within physics, nanoscience, or materials science. 

    Candidates with the following qualifications are preferred:

    • Experience with DFT simulations
    • Knowledge in solid state-physics or chemistry
    • Experience with Machine Learning 

    Further qualifications:

    • Experience with complex oxides and defect chemistry
    • Good communication skills in English 
    • Ability to work both independently and in a team 

    PhD 2:  The fabrication of the freestanding membranes and assembling artificial heterointerfaces

    Responsibilities and qualifications
    The successful candidate will synthesize, transfer, stack, and twist of freestanding oxide membranes into artificial heterostructures oxide films. The vision is to provide a method for rational design of defects that emerge at interfaces upon stacking and twisting non-matched membranes. Here, we will focus on ionic and electronic oxide interfaces grown by pulsed laser deposition (PLD). These require advanced experimental probes to shed light on the underlying physical and chemical processes using local electrical and ionic transport and structural properties of individual membranes and membrane stacks. Understanding the relationship between the strain and the properties at the interfaces is key to understanding the interface's transport. The advent of freestanding oxide membrane presents enticing possibilities to apply external stimuli (strain, light etc.) and develop additional degrees of freedom to manipulate the properties.

    Candidates should be highly motivated and must hold a master's degree (or equivalent), preferably in a physics, nanoscience, or materials science-related discipline.

    Candidates with the following qualifications are preferred:

    • Experience working with complex oxides
    • Knowledge in solid-state physics or chemistry
    • Experience with PLD growth of oxide heterostructures
    • Experience with clean-room fabrication techniques
    • Experience with transport measurements skills is beneficial

    Further qualifications:

    • Good understanding of electrical and structure and measurements
    • Good communication skills in English 
    • Ability to work both independently and in a team 

    Please specify which of the two PhD positions you are applying for.

    Approval and Enrolment
    The scholarship for the PhD degree is subject to academic approval, and the candidate will be enrolled in one of the general degree programmes at DTU. For information about our enrolment requirements and the general planning of the PhD study programme, please see DTU's rules for the PhD education . 

    We offer
    DTU is a leading technical university globally recognized for the excellence of its research, education, innovation and scientific advice. We offer a rewarding and challenging job in an international environment. We strive for academic excellence in an environment characterized by collegial respect and academic freedom tempered by responsibility.

    Salary and terms of employment
    The appointment will be based on the collective agreement with the Danish Confederation of Professional Associations. The allowance will be agreed upon with the relevant union. The period of employment is 3 years.

    You can read more about career paths at DTU here .

    The expected starting date is August 2023.

    Further information
    Please contact Prof. Nini Pryds, +45 4677 5752  and Prof. Juan Maria García Lastra  for further information.

    Please do not send applications to this e-mail address, instead apply online as described below.

    If you are applying from abroad, you may find useful information on working in Denmark and at DTU at DTU – Moving to Denmark . Furthermore, you have the option of joining our monthly free seminar “PhD relocation to Denmark and startup “Zoom” seminar ” for all questions regarding the practical matters of moving to Denmark and working as a PhD at DTU. 

    Application procedure
    Please complete your online application no later than 1 June 2023 (Danish time).

    Applications must be submitted as one pdf file containing all materials to be given consideration. To apply, please open the link "Apply online," fill in the online application form, and attach all your materials in English in one pdf file. The file must include:

    • A letter motivating the application (cover letter)
    • Curriculum vitae
    • Grade transcripts and BSc/MSc diploma (in English) including official description of grading scale

    Please specify which of the two PhD positions you are applying for.

    Applications received after the deadline will not be considered.

    All interested candidates irrespective of age, gender, race, disability, religion or ethnic background are encouraged to apply.

    DTU Energy is focusing on functional materials and their application in sustainable energy technology. Our research areas include fuel cells, electrolysis, solar cells, You may apply prior to ob­tai­ning your master's degree but cannot begin before having received it.

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    DTU develops technology for people. With our international elite research and study programmes, we are helping to create a better world and to solve the global challenges formulated in the UN’s 17 Sustainable Development Goals. Hans Christian Ørsted founded DTU in 1829 with a clear mission to develop and create value using science and engineering to benefit society. That mission lives on today. DTU has 13,500 students and 6,000 employees. We work in an international atmosphere and have an inclusive, evolving, and informal working environment. DTU has campuses in all parts of Denmark and in Greenland, and we collaborate with the best universities around the world.

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