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鈥檚 shape defines the mesospins鈥� 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/) and 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 at the University of Patras, Greece where I am originally from.

My Batchelor鈥檚 thesis project was about the growth of gold nanoparticles and their properties鈥� 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 (Prof. P. Fumagalli) at Freie Universitaet Berlin.
For my Master鈥檚 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 (). 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鈥檚 and Master鈥檚 projects supervised by

Awards:

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

List of Publications:

鈥�Optical interpretation for plasmonic adjustment of nanostructured Ag-NiO thin films鈥�, 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, , 2021.
鈥�Quantum confinement effects of thin ZnO films by experiment and theory鈥�, 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; , 2020.
鈥�Paramagnetic gold in a highly disordered Au-Ni-O alloy鈥欌€�, A. Stamatelatos, P. Poulopoulos, A. Goschew, P. Fumagalli, E. Sarigiannidou, L. Rapenne, S. Grammatikopoulos, F. Wilhelm, A. Rogalev, Scientific Reports 9 (1), 13137; , 2019.
鈥�Development of Perpendicular Magnetic Anisotropy in Ni/NiO Multilayers after Soft Thermal Treatment鈥欌€�, D. I. Anyfantis, E. Sarigiannidou, L. Rapenne, A. Stamatelatos, D. Ntemogiannis, V. Kapaklis, P. Poulopoulos, IEEE Magnetics Letters 10, 6104105; , 2019.
鈥�Microstructure and plasmonic behavior of self-assembled silver nanoparticles and nanorings鈥欌€�, 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 ; , 2019.
鈥�A Study of Quantum Confinement Effects in Ultrathin NiO Films Performed by Experiment and Theory鈥欌€�, Christos S. Garoufalis, Alexandros Barnasas, Alkeos Stamatelatos, Vagelis Karoutsos, Spyridon Grammatikopoulos, Panagiotis Poulopoulos and Sotirios Baskoutas, Materials, 11, 949; , 2018.
鈥�Analysis of localized surface plasmon resonances in gold nanoparticles surrounded by copper oxides鈥欌€�, A. Stamatelatos, A. Sousanis, A. G. Chronis, M. M. Sigalas, S. Grammatikopoulos, and P. Poulopoulos, Journal of Applied Physics 123, 083103; , 2018.
鈥�Growth of Au Nanoparticles in NiO via Short Annealing of Precursor Material Thin Film and Optimization of Plasmonics鈥�, S. Grammatikopoulos, A. Stamatelatos, A. Delimitis, A. Sousanis, A. Chrisanthopoulou, D. Trachylis, C. Politis and P. Poulopoulos, Phys. Status Solidi A, 214, 1700303, , 2017.

List of Participation in Conference Posters and Oral Presentations:

鈥�Probing thermally activated dynamics in squared artificial spin ices鈥�, 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.
"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.
鈥�Probing thermally activated dynamics in Artificial Mesospin Ising Chains by means of XPCS鈥�, A. Stamatelatos, N. Strandqvist, R. Rowan Robinson, V. Kapaklis, B. Hj枚rvarsson, Steadman, R. Fan, O. Bikondoa, T. Hase, Poster presentation at the 16th SXNS, Lund, Sweden, January 11 – 14, 2022.
鈥�Growth of self-assembled metallic nanoparticles for optimization of localized surface plasmon resonances (LSPRs)鈥�, 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.
"Ni/NiO multilayers: Magnetic Anisotropies and Influence of Thermal Treatment鈥�, 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.
鈥�Determination of Magnetic Moment Profile of Eus/Co/Ni/Co Multilayers for Spintronics鈥�, 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.
鈥�Preparation and Characterization of Nanostructured Thin Films of Metal Alloys鈥�, 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.
鈥�Synthesis, Properties and Environmental Applications of Nanostructured Ag-ZnO鈥�, 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.
鈥�Unusual Magnetic Response of Au in a Plasmonic Material鈥�, 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.
鈥�Room temperature magnetic moment profile of EuS in EuS/Co/Ni multilayers measured by XRMS鈥欌€�, 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.
鈥�Natural magnetic multilayers: Growth and magnetism鈥欌€�, 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.