Institute of High Pressure Physics

With great sorrow, we announce the passing away of Jean-Louis Robert, retired professor of physics at the University of Montpellier and our longtime Friend, on September 7th. Professor Robert's professional career was closely associated with research on semiconductor materials, ranging from fundamental studies to practical applications. The close connection between research and applications was of particular importance to Professor Robert and led to the practical utilization of the results of the basic research in the industry.

Dr hab. inż. Julita Smalc-Koziorowska from the Laboratory of Semiconductor Characterization will give an invited talk on E-MRS Fall Meeting next week. The talk is entitled „The role of metal vacancies in thermal degradation of InGaN” and is a part of Symposium U "Defect-induced effects in low-dimensional and novel materials" on September 18, 2023.

The 2023 Fall Meeting of the European Materials Research Society (E-MRS) will take place from September 18 to 21, 2023 at the main campus of the University of Technology in Warsaw (Poland) and will consist of 24 parallel symposia with invited speakers, oral and poster presentations assorted by one plenary session to provide an international forum for discussing recent advances in the field of materials science.

The research team of Dr. Singh from NL-6 Laboratory of Superconductors has recently published two interesting publications on iron-based superconductors (FBS); both in an open access journal Materials (Impact factor 3.4).

In the first paper, the effect of cometal addition has been studied and reported for FBS at ambient pressure, where the enhancement of the superconducting transition (T_c) and critical current (J_c) properties were observed due to the improvement of the intergrain connections and pinning centres. This paper is published by M. Manasa, M. Azam, T. Zajarniuk, R. Diduszko, T. Cetner, A. Morawski, A. Wiśniewski, and Shiv J. Singh entitled “Cometal Addition Effect on Superconducting Properties and Granular Behaviours of Polycrystalline FeSe_0.5Te_0.5” (Materials 16, 2892 (2023)  https://doi.org/10.3390/ma16072892).

In the second work, optimization of Fe(Se,Te) physical properties was carried out utilizing the high gas pressure and high-temperature approach (HP-HTS). In comparison to the ambient pressure approach, HP-HTS under optimal growth conditions significantly improved the critical current density, the pinning properties, and the transition temperature. This study demonstrates that the high-pressure synthesis method can be a novel approach to studying FBS materials in order to improve sample quality, achieve further superconducting property enhancements, and advance the development of their magnetic applications, particularly for superconducting wires and tapes. This paper is published by M. Azam, M. Manasa, T. Zajarniuk, R. Diduszko, T. Cetner, A. Morawski, J. Więckowski, A. Wiśniewski, and Shiv J. Singh entitled “High-Pressure Synthesis and the Enhancement of the Superconducting Properties of FeSe_0.5Te_0.5” (Materials 16, 5358 (2023) https://doi.org/10.3390/ma16155358).

Note that this is EDITOR's CHOICE ARTICLE, selected by Editors to be particularly interesting to readers and important in the respective research area.

Fig. The variation of hexagonal phase (H), room temperature resistivity (ρ_300K), Residual resistivity ratio (RRR), the onset transition temperature (T_c^onset), transition width (ΔT) and critical current density (J_c) with synthesis pressure.

MBE Laboratory will collaborate with Warsaw University on the Horizon Europe Pathfinder project “Neuromorphic Polariton Accelerator”, acronym: PolArt. The goal of the project, leaded by prof. Barbara Piętka, is to demonstrate a new way to build artificial intelligence-dedicated circuits using polariton neural networks as optical accelerators. Prof. Czesław Skierbiszewski team will be focused on the design, fabrication and integration of the micro-LEDs and their arrays, that are the key elements to inject and modulate the signal in the waveguides.

The project aims to build a network that performs binary operations based on polariton microcavities. The basic element that enables effective binary operations are semiconductor microcavities. Strong coupling of the microcavity modes with excitons result in gigantic nonlinearities that are required for efficient calculations. The fact that polaritons operating room temperature was recently demonstrated, promises to have a real impact on the technologies of the future. Research units involved in the project have recently shown that this state of matter is extremely interesting in terms of speed and efficiency when used to implement artificial neural networks.

Thanks to this new concept device, complex applications related to neural-like processing, will be efficiently implemented, therefore enabling neuromorphic computation to be done in small devices that cannot rely on remote, large bandwidth connection. This proposal benefits from the contribution of several complementary partners coming from many different research areas (material science, physics, optics, chemistry, genetics) and industrial participants that assure the interdisciplinarity and technological oriented target.

Fig. (a) Scheme of XOR gate based on polariton microcavity (after R. Mirek et al. Nano Letters, 21, 37152021, 2021). (b) Scheme of the polaritonic neuromorphic accelerator designed for room temperature operation with perovskite waveguides with signal modulated by μ-LEDs arranged into arrays.