RESEARCH INTERESTS

Condensed Matter Physics, Raman/IR Spectroscopy, XRD, XAS/XMCD, MOKE, MBE Growth, ARPES, DFT, Atomistic Spin Simulations, Multiferroics, 2D Materials, Topological Materials, Magnetic & Skyrmionic Materials

ABOUT/BIOGRAPHY

Dr. Panagiotis Pappas acquired his Ph.D. from the National Technical University of Athens. The results of his Raman and XRD experiments with in-situ application of magnetic and electric field led to the discovery of a strong spin lattice coupling at elevated temperatures in ETO and the emergence of a new polar phase on the surface of epitaxially grown ETO after the application of an electric field. 

For his Ph.D. research he received a three-year scholarship from the State Scholarships Foundations (ΙΚΥ) Program for Strengthening Human Resources Research Potential via Doctorate Research (MIS-5000432).

During his Ph.D. he designed and performed a series of Raman studies with in-situ application of external electric and magnetic fields at ambient conditions and at low temperatures in order to study the induced lattice effects and the potential emergence of multiferroicity. He also studied bulk ETO samples at high hydrostatic pressures with Raman spectroscopy. Furthermore, he has participated in ten synchrotron-based experiments involving: structural characterization by Powder XRD/Grazing Incidence XRD with in situ application of electric and magnetic field at low temperatures, lattice/phonon studies by FTIR and UV Raman experiments on ETO epitaxial film with in-situ application of magnetic fields at Elettra Sincrotrone Trieste. Local magnetic properties and electronic properties studied by X-ray Magnetic Circular Dichroism (XMCD) and X ray Absorption Spectroscopy (XAS) on bulk and epitaxial ETO films with in-situ application of magnetic field at SOLARIS synchrotron in Krakow. Local structure and stoichiometry studies by EXAFS/XANES experiments on bulk ETO with in-situ magnetic field performed at ESRF Grenoble. Most of them were full funded by CERIC-ERIC and Elettra Sincrotrone Trieste.

He has also experience in ab initio DFT calculations focused on 2D materials. 

Currently his research interest involves the MBE growth of 2D magnetic materials/topological insulators heterostructures in order to investigate their magnetic interactions which correlated with skyrmion formations and are expected to be useful for novel spintronic devices.  He focuses on their characterization with Kerr effect microscopy, X-ray Photoemission Spectroscopy (XPS) and Angle-Resolved Photoemission Emission Spectroscopy (ARPES). He is also involved in Hall effect measurements and the manipulation of magnetization with the spin transfer torque effect.

PUBLICATIONS

Pappas, P., Calamiotou, M., Polentarutti, M., Bais, G. and Bussmann-Holder, A. and Liarokapis, E., Magnetic field driven phase transitions in EuTiO3 JOURNAL OF PHYSICS-CONDENSED MATTER, Volume 34, 2022 [doi]

Tsipas, P., Pappas, P., Symeonidou, E., Fragkos, S., Zacharaki, C., Xenogiannopoulou, E., Siannas, N. and Dimoulas, A., Epitaxial HfTe2Dirac semimetal in the 2D limit APL Materials, Volume 9, Article Number: 101103, 2021 [doi]

Pappas, Panagiotis, Liarokapis, Efthymios and Calamiotou, Maria and Bussmann-Holder, Annette, Magnetic interactions and the puzzling absence of any Raman mode in EuTiO3 JOURNAL OF RAMAN SPECTROSCOPY, Volume 52, Pages: 914-924, 2021 [doi]

Pappas, P., Calamiotou, M., Koehler, J., Bussmann-Holder, A. and Liarokapis, E., Nonlinear electrostrictive lattice response of EuTiO3 APPLIED PHYSICS LETTERS, Volume 111, 2017 [doi]

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