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Department of Physics

Alkaios Stamatelatos

Research Activities:

The research purpose of my PhD is to investigate the dynamical behavior of nanostructured magnetic artificial arrays by means of X-rays. More specifically, each element of those magnetic arrays, may act as a single mesospins, which means that novel magnetic metamaterials can be created and be tailored, in which to study geometric frustration. The element’s shape defines the mesospins’ anisotropy with the material defining the spin dimensionality and thermal properties. Therefore, artificial spin ices (ASIs) in which the elements and their pairwise interactions are modified, enable fundamental physics and new pathways towards future technological exploitation to be explored, which makes use of the analogue between the elemental mesospin and atomic magnetic spins. For this project we use as the base material the thermally active Fe/Pd in which the ordering temperature is tuned through composition. In the thermal regime the collective and local behavior is associated with individual islands reversing, introducing defects which evolve with temperature.

Although, direct imaging techniques (MFM/PEEM) have been realized for studying metastable states, those are limited for dynamically evolving systems as acquisition times are necessarily long. Therefore, we aim to develop a metrology, by combining high spatial and temporal resolution, based on coherent scattering and X-ray photon correlation spectroscopy (XPCS). XPCS is a novel technique which uses coherent X-ray beam coming from a very brilliant source such as a synchrotron radiation facility, and measures any occurred dynamic fluctuation in the ASIs for a given timescale. Due to the coherent scattering, the latter produces a speckled pattern in the reciprocal space which time correlation functions are implemented for its interpretation.

Lastly, in this project we will build and develop suitable modelling frameworks to describe ASIs structures with hierarchical complexity i.e. from Ising chains to multi-element arrays. The research is being carried out in collaboration between our group (Prof. Thomas HaseLink opens in a new window/Dr. Oier BikondoaLink opens in a new window) and Materials PhysicsLink opens in a new window group at Uppsala University. The X-ray experiments will be performed at central synchrotron facilities.

Research Background:

I studied both for my BA and MSc in the department of Materials ScienceLink opens in a new window at the University of Patras, Greece where I am originally from.

  • My Batchelor’s thesis project was about the growth of gold nanoparticles and their properties’ investigation by means of scanning near field optical microscopy (SNOM). I prepared the nanoparticles by using a magnetron sputtering and I investigated their structural and optical properties by means of SNOM. The project was carried out in collaboration with the department of PhysicsLink opens in a new window (Prof. P. Fumagalli) at Freie Universitaet Berlin.
  • For my Master’s thesis project I investigated the characterisation of various magnetic thin- and multilayer- films by using conventional X-rays and synchrotron radiation. In particular, the films (Au/Ni/NiO, Ni/NiO, Ni/Co/EuS/Co) were prepared by a DC/RF magnetron sputtering, sublimation and an e-beam evaporation respectively. For their characterization we exploited various techniques such as XRR, HRTEM, SQUID VSM and XMCD as well as by using simulation tools (GenX). Part of the experiments were carried out at the FUB, Uppsala University, CNRS Grenoble and ESRF. Fruitful results were derived regarding their growth and magnetic properties i.e. investigation of EuS induced magnetic moments.

Both Batchelor’s and Master’s projects supervised by Prof. Panagiotis Poulopoulos.Link opens in a new window

Awards:

  • 2017 – 2019: Awarded with the “Andreas Mentzelopoulos Scholarships for the University of Patras” grant for two years in a row for exceptional performance in academics.
  • 2016: Awarded with “Erasmus + Placement” funded traineeship mobility as part of my trimester placement at Freie Universitaet Berlin.

List of Publications:

  1. “Optical interpretation for plasmonic adjustment of nanostructured Ag-NiO thin films”, A. Stamatelatos, M. Tsarmpopoulou, A. G. Chronis, N. Kanistras, D.I. Anyfantis, E. Violatzi, D. Geralis, M.M. Sigalas, P. Poulopoulos, S. Grammatikopoulos, International Journal of Modern Physics B 35 (6), 2150093, doi: 10.1142/S0217979221500934Link opens in a new window, 2021.
  2. “Quantum confinement effects of thin ZnO films by experiment and theory”, A. Barnasas, C.S. Garoufalis, N. Kanistras, A. Ntagas, D.I. Anyfantis, A. Stamatelatos, V. Kapaklis, N. Bouropoulos, E. Mystiridou, P. Poulopoulos, S. Baskoutas, Physica E 120, 114072; https://doi.org/10.1016/j.physe.2020.114072Link opens in a new window, 2020.
  3. “Paramagnetic gold in a highly disordered Au-Ni-O alloy’’, A. Stamatelatos, P. Poulopoulos, A. Goschew, P. Fumagalli, E. Sarigiannidou, L. Rapenne, S. Grammatikopoulos, F. Wilhelm, A. Rogalev, Scientific Reports 9 (1), 13137; https://doi.org/10.1038/s41598-019-49457-7Link opens in a new window, 2019.
  4. “Development of Perpendicular Magnetic Anisotropy in Ni/NiO Multilayers after Soft Thermal Treatment’’, D. I. Anyfantis, E. Sarigiannidou, L. Rapenne, A. Stamatelatos, D. Ntemogiannis, V. Kapaklis, P. Poulopoulos, IEEE Magnetics Letters 10, 6104105; doi: 10.1109/LMAG.2019.2925315Link opens in a new window, 2019.
  5. “Microstructure and plasmonic behavior of self-assembled silver nanoparticles and nanorings’’, A. G. Chronis, A. Stamatelatos, S. Grammatikopoulos , M. M. Sigalas, V. Karoutsos, D. M. Maratos, S. P. Lysandrou, D. Trachylis, C. Politis, and P. Poulopoulos, J. Appl. Phys. 125, 023106 ; https://doi.org/10.1063/1.5050467Link opens in a new window, 2019.
  6. “A Study of Quantum Confinement Effects in Ultrathin NiO Films Performed by Experiment and Theory’’, Christos S. Garoufalis, Alexandros Barnasas, Alkeos Stamatelatos, Vagelis Karoutsos, Spyridon Grammatikopoulos, Panagiotis Poulopoulos and Sotirios Baskoutas, Materials, 11, 949; doi:10.3390/ma11060949Link opens in a new window, 2018.
  7. “Analysis of localized surface plasmon resonances in gold nanoparticles surrounded by copper oxides’’, A. Stamatelatos, A. Sousanis, A. G. Chronis, M. M. Sigalas, S. Grammatikopoulos, and P. Poulopoulos, Journal of Applied Physics 123, 083103; doi: 10.1063/1.5021402Link opens in a new window, 2018.
  8. “Growth of Au Nanoparticles in NiO via Short Annealing of Precursor Material Thin Film and Optimization of Plasmonics”, S. Grammatikopoulos, A. Stamatelatos, A. Delimitis, A. Sousanis, A. Chrisanthopoulou, D. Trachylis, C. Politis and P. Poulopoulos, Phys. Status Solidi A, 214, 1700303, doi: 10.1002/pssa.201700303Link opens in a new window, 2017.

List of Participation in Conference Posters and Oral Presentations:

  1. “Probing thermally activated dynamics in squared artificial spin ices”, A. Stamatelatos, C. Vantaraki, C. Mazzoli, A. Barbour, V. Kapaklis, O. Bikondoa, T. Hase, Poster presentation at the Frontiers in Artificial Spin Ice Workshop 2023, Lenzburg, Switzerland, June 14 – 16, 2023.
  2. "Probing thermally activated dynamics in artificial spin ices by means of XPCS", A. Stamatelatos, O. Bikondoa, C. Vantaraki, N. Strandqvist, C. Mazzoli, R. Fan5, P. Steadman, V. Kapaklis and T.P.A. Hase, oral talk presented by A. Stamatelatos at COHERENCE 2022 : International Conference on Phase Retrieval and Coherent Scattering, Shanghai, China, July 5 - 9, 2022.
  3. “Probing thermally activated dynamics in Artificial Mesospin Ising Chains by means of XPCS”, A. Stamatelatos, N. Strandqvist, R. Rowan Robinson, V. Kapaklis, B. Hjörvarsson, Steadman, R. Fan, O. Bikondoa, T. Hase, Poster presentation at the 16th SXNS, Lund, Sweden, January 11 – 14, 2022.
  4. “Growth of self-assembled metallic nanoparticles for optimization of localized surface plasmon resonances (LSPRs)”, A. Stamatelatos, A. G. Chronis, M. M. Sigalas, S. Grammatikopoulos, P. Poulopoulos, Oral talk presented by A. Stamatelatos at 34th annual Panhellenic Conference on Solid State Physics and Materials Science, Patras, Greece, September 11 – 14, 2019.
  5. "Ni/NiO multilayers: Magnetic Anisotropies and Influence of Thermal Treatment”, D.I. Anyfantis, E. Sarigiannidou, L. Rapenne, A. Stamatelatos, D. Ntemogiannis, V. Kapaklis and P. Poulopoulos, Oral talk presented by D.I. Anyfantis at 34th annual Panhellenic Conference on Solid State Physics and Materials Science, Patras, Greece, September 11 – 14, 2019.
  6. “Determination of Magnetic Moment Profile of Eus/Co/Ni/Co Multilayers for Spintronics”, A. Stamatelatos, A. Goschew, P. Fumagalli, Th. Kehagias, B. Lindgren, V. Kapaklis, F. Wilhelm, A. Rogalev, P. Poulopoulos, Poster Presentation at 6th IC4N, Corfu, Greece, June 30 – July 3, 2019.
  7. “Preparation and Characterization of Nanostructured Thin Films of Metal Alloys”, A. Stamatelatos, N. Kanistras, D. Anyfantis, E. Violatzi, D. Geralis, S. Grammatikopoulos, M. Tsarmpopoulou, M.M. Sigalas, P. Poulopoulos, Poster Presentation at 6th IC4N, Corfu, Greece, June 30 – July 3, 2019.
  8. “Synthesis, Properties and Environmental Applications of Nanostructured Ag-ZnO”, A. Barnasas, N. Kanistras, A. Stamatelatos, N. Dimopoulou, V. Karoutsos, E. Mystiridou, N.Bouropoulos, M.V. Karavasilis, C. Aggelopoulos, C.D. Tsakiroglou, P. Poulopoulos, Poster Presentation at 6th IC4N, Corfu, Greece, June 30 – July 3, 2019.
  9. “Unusual Magnetic Response of Au in a Plasmonic Material”, P. Poulopoulos, A. Stamatelatos, A. Goschew, P. Fumagalli, E. Sarigiannidou, L. Rapenne, C. Opagiste, S. Grammatikopoulos, F. Wilhelm, A. Rogalev, Oral Talk presented by P. Poulopoulos at 6th International Conference from Nanoparticles and Nanomaterials to Nanodevices and Nanosystems (6th IC4N), Corfu, Greece, June 30 – July 3, 2019.
  10. “Room temperature magnetic moment profile of EuS in EuS/Co/Ni multilayers measured by XRMS’’, A. Goschew, A. Stamatelatos, P. Poulopoulos, F. Wilhem, A. Rogalev and P. Fumagalli, Oral Talk presented by A. Goschew at Joint MMM-INTERMAG, Washington DC, USA, January 14-18, 2019.
  11. “Natural magnetic multilayers: Growth and magnetism’’, P. Poulopoulos, D.I. Anyfantis, D. Ntemogiannis, A. Stamatelatos, A. Delimitis, S.D. Pappas, V. Kapaklis, Poster Presentation at EUROMAT 2017, European Congress and Exhibition on Advanced Materials and Processes, Thessaloniki, Greece, September 17-22, 2017.

Teaching:

Problem class tutor for the 1st year undergraduate physics course “Mathematics for Physicists”

Interests:

Except from science I enjoy listening to music, playing football, reading history books and hiking.


Profile Picture

Position: PhD student

Started: October 2020

Supervisor: Prof. Thomas Hase

Funding: EPSRC

Write to:

Department of Physics, University of Warwick, Coventry, CV4 7AL

Contact Details:

Email: alkaios dot stamatelatos at warwick dot ac dot uk

Office: MAS 3.09

Links:

googleimageLink opens in a new window rgLink opens in a new window inLink opens in a new window

SEM SASI

Figure 1: SEM image of Square Artificial Spin Ice

Chains

Figure 2: SEM image of Ising-like chains

XCPS

Figure 3: Experimental diffraction pattern recorded for Ising-like chains