PhD Studies

Research groups at the Institute of Physics, University of Tartu (IPUT) are looking for eligible candidates to begin PhD research on the following topics:

• Memory effects in nanocrystalline metal oxide films and their nanolaminates.
  Resistive switching phenomena in different dielectric multilayers will be investigated during the doctoral studies. The goal of the studies is to seek and find multistate structures most suited to the possible applications in computer memories to store and elaborate data and information. During the PhD studies structure with optimized parameters will be selected, in order to thoroughly explore electrical properties of the multilayer stacks and examine the performance of memory cells. Design of memory matrices with high packing density will be aimed at, when selecting new materials for this purpose.
  Please contact Dr. Kaupo Kukli (kaupo.kukli [ät] ut.ee). Co-supervisers Aile Tamm and Jekaterina Kozlova.
• A modern shape for the nonlocal Nambu–Jona-Lasinio model
  In this project we consider the Nambu–Jona-Lasinio (NJL) model as a useful tool to investigate the low energy behaviour of hadronic states in the framework of an effective field theory. We show that the nonlocal version of the model is renormalisable and supports the confinement of quarks within the hadronic state. Using this model, we calculate the masses of different hadronic low energy states. In addition, we look for applications of this model to gravity and other related branches of theoretical physics phenomenology.
  Please contact Dr. Stefan Groote (stefan.groote [ät] ut.ee).
• Cosmic Phase Transitions in Multi-Scalar Potentials.
  Future space-based gravitational wave detectors such as LISA will enable us to see the cosmic phase transitions in the early Universe. In analogue to sound waves from the boiling of water, the first-order cosmic phase transitions generate gravitational waves. In the Standard Model, which describes the particles known to us, the only scalar field is the Higgs boson. The Standard Model Higgs phase transition is a cross-over and does not generate any gravitational waves. In extensions of the Standard Model with new scalars, tunnelling of the scalar field through the barrier between two minima can result in a first-order phase transition. If the scalar potential has more minima, then two phase transitions can occur one after another, and the resulting gravitational wave spectrum will have two distinct peaks. In this way, the gravitational wave signal can be put to direct correspondence with the minimum structure of the scalar potential. Especially interesting are models with classically scale-invariant potentials, where minima are generated via quantum corrections. Such models may explain the puzzling lightness of the Higgs boson and quite generally promise to produce sizeable gravitational waves signals in phase transitions. Two-step phase transitions in such models have not been studied at all. The aim of the project will be to study two-step phase transitions in multi-scalar potentials, in particular classically scale-invariant potentials.
  Please contact Dr. Kristjan Kannike (kristjan.kannike [ät] kbfi.ee). Co-supervisers Laur Järv and Luca Marzola.
• Study of synthesis-structure-properties relations to develop CeO₂-based nanomaterials for biological and electrochemical applications.
  Nanostructured cerium dioxide proved to be one of the most promising materials for many applications related to electronic and ionic mobility due to its oxygen nonstoichiometry, uniquely low temperature diffusion of oxygen anions in the lattice and high sensitivity of surface condition to external influences. The objective of this project is to systematically study “synthesis-structure-properties” relations during liquid phase synthesis of nanostructured ceria materials. The main tasks of the project include (i) synthesis of CeO2 nanoparticles by homogeneous hydrolysis of cerium (III) and cerium (IV) compounds in prehydrothermal and hydrothermal conditions, as well as in non-aqueous solvents, (ii) study of antiviral and catalytical properties of synthesized ceria particles in the form of colloids and spin-coated films, (iii) establishing the correlations between the preparation technique and activity of the material in the chosen process. It will help to reach the understanding how nanoceria works in different application systems, which centres (structural units) are responsible for its activity, how they form during synthesis and how synthetic conditions promote or inhibit their formation. This will allow for directed synthesis of nanoceria-based antiviral, catalytical and high temperature ion membrane materials with properties optimized for specific application.
  Please contact Dr. Alexander Vanetsev (alexander.vanetsev [ät] ut.ee). Co-supervisers Angela Ivask and Glen Kelp.
• Wide Gap Functional Nano- and Microparticles for Medical Applications.
  The goal of research is to develop functional nanomaterials for medical applications based on the synergistic effect of X-ray irradiation and other therapeutic and diagnostic approaches. These heavy nanoparticles, delivered into the tumor tissue, create UV scintillation photons under X-ray excitation for the increase of efficiency of killing cancer cells during radiotherapy treatment. Pr3+ doped with orthophosphates emitting in UV-C will be studied to understand the interaction of different rare earth dopants upon high energy excitation and provide a detailed clarification of energy relaxation pathways subsequent to the absorption of X-rays. Wise selection of the rare earth co-dopants (e.g. Nd3+, Gd3+, Er3+, or Yb3+) in LuPO4, LaPO4 and YPO4 hosts allows to create novel materials for multifunctional imaging, diagnosis and treatment applications in medicine.
  Please contact Dr. Marco Kirm (marco.kirm [ät] ut.ee).
• Structure and dynamics of photoactive proteins studied by (in situ-) neutron scattering methods.
  Neutron scattering methods are well-suited for direct investigations of dynamics and solution structures of proteins under nearly native conditions. In addition, in-situ experiments employing external triggers permit studies of specific functional states or of even complete functional processes in proteins. Some remarkable examples of structure-dynamics-function correlations include dynamics-mediated electron transfer in photosystems, the adaptation of protein function to high temperatures or photoprotective mechanisms in cyanobacterial light-harvesting antennae. As to the latter, the Orange Carotenoid Protein (OCP) involved in photoprotection of the cyanobacterial light-harvesting apparatus is currently a subject of an intense scientific debate. OCP is known to undergo a light-induced structural change from its inactive orange state OCPo to an active red state OCPr, which can be initiated by illumination using a laser wavelength of 450 nm at 300 K. While only the ground state crystal structure of OCP is known, the light-induced changes are still disputed. Especially, no high-resolution structures are available for the active state nor for the specific conformations that allow a binding of OCP to other protein complexes involved in photoprotection. The aim of this PhD project is to elucidate both, the structures of OCP in its active and complex-forming states as well as a potential functional importance of OCP protein dynamics as a prerequisite for undergoing large-scale structural changes. In order to achieve this goal, a number of neutron scattering techniques have to be combined: i) small angle neutron scattering with external triggers to study the structure of OCP in its different (non-crystallized) conformations, ii) neutron spectroscopy to investigate the protein dynamics, and iii) complementary molecular dynamics simulations to achieve structural models of the observed protein dynamics. We anticipate that this work will lead to a detailed understanding of the molecular mechanisms of OCP function, but also contribute to the development of complementary neutron scattering methods and their combination with theory.
  Please contact Dr. Jörg Pieper (jorg.pieper [ät] ut.ee). Co-superviser Maksym Golub.
• Graphene- based gas sensors on MEMS platforms.
  The aim of the project is to integrate the gas sensors based on functionalised single-layer graphene onto CMOS chips, micro-hotplates and -lightplates. Methods to combine multiple functionalisations on a single chip will be investigated. The project is supported by Graphene Flagship.
  Please contact Dr. Raivo Jaaniso (raivo.jaaniso [ät] ut.ee). Co-supervisers Margus Kodu and Harry Alles.