Seminar Speaker

Lynette Keeney 

Venue

Room G06, Kane Science Building, UCC

Time/Date 

4pm / Monday, 19 Jan, 2026

Title

Routes to Multiferroicity and Emergent Topological States in Layered Oxide Thin Films

Abstract

Single-phase multiferroics, which combine ferroelectric and ferromagnetic order in a single material, offer powerful new routes to data manipulation and storage while opening opportunities for exploring unconventional chemistry and physics. Yet, such materials remain exceptionally scarce due to the classic incompatibility between the d⁰ electronic configurations that favour ferroelectricity and the dⁿ configurations required for ferromagnetism. In our work, we demonstrated a rare example of a room-temperature magnetoelectric multiferroic through the design of a new layered Aurivillius compound, Bi₆Ti_xFe_yMn_zO₁₈ (B6TFMO; x =  2.80 to 3.04; Y = 1.32 to 1.52; Z = 0.54 to 0.64). By judiciously combining A-site Bi³⁺ cations with mixed B-site species (Ti⁴⁺, Fe³⁺, Mn^3+/4+), we stabilised ferroelectric and ferromagnetic order within a single structural phase.

More recently, we uncovered remarkable polar topological structures that emerge near naturally occurring disruptions in the B6TFMO layering. These structural discontinuities: out-of-phase boundary (OPB) defects, locally modify elastic strain and electrostatic energy landscapes, producing strongly inhomogeneous polarisation fields. Atomic-resolution scanning transmission electron microscopy and polar-displacement mapping reveal nominally charged domain walls and continuous rotations of the polarisation vector, giving rise to exotic polar vortex-like configurations. These previously “hidden” topologies arise intrinsically, without engineered interfaces or external strain tuning.

Density functional theory and aberration-corrected microscopy confirm that OPB defects act as local symmetry-breaking centres, generating polar discontinuities and complex ferroic textures. However, uncontrolled defect propagation leads to variability in OPB defect type and density, motivating systematic defect-engineering strategies. To this end, B6TFMO thin films were grown by chemical vapour deposition on vicinal sapphire substrates with controlled miscut angles (0.2°–10°). X-ray diffraction and STEM show that increasing the miscut enhances OPB defect density, which directly impacts ferroelectric domain size, polarisation orientation, and switching behaviour. By further tuning supersaturation during growth, we induce spiral-like growth features in which OPB defects delineate the edges of pyramidal growth features. These defect-mediated modifications lead to local symmetry lowering, strain redistribution, and a four-fold reduction in the minimum vertical switching voltage.

These findings highlight OPB defects as powerful, intrinsic drivers of topological ferroic states in layered multiferroics. The resulting two-dimensional polar textures possess characteristic length scales of ~5 nm, far smaller than those of magnetic analogues (10–100 nm), providing a pathway to ultracompact, energy-efficient information storage and next-generation nanoelectronic and spintronic technologies.

Seminar Speaker

Ingrid Pelisoli

Venue

Room G06, Kane Science Building, UCC

Time/Date 

4pm / Monday, 24 Nov, 2025

Title

White dwarf pulsars and (possibly) related objects

Abstract

White dwarf stars are the most common outcome of stellar evolution. About a third of them are found in binary systems, reflecting the fact that multiplicity is frequent amongst stars. One of the most remarkable white dwarf binary systems identified to date is AR Scorpii, which is composed of a red dwarf star and a rapidly spinning, magnetised white dwarf in a 3.56-hour orbit. It shows strongly pulsed emission on the white dwarf spin period of 2 minutes over a broad range of wavelengths, from radio to X-rays, which led to it being known as a white dwarf pulsar. However, unlike neutron star pulsars, where no companion is required, it is understood that binary interaction is what triggers AR Sco’s pulses. Despite its fascinating characteristics, AR Sco remained for several years the only known system of its kind, preventing us from testing the models that could explain its formation and observed properties. In this talk, I will present the discovery of two new white dwarf pulsars that have established the existence of these systems as a class and discuss their possible connection with another intriguing new class of systems, long-period radio transients.

Seminar Speaker

Dr. Katarzyna Komolibus 

Dr. Katarzyna Komolibus is a senior researcher in the Biophotonics team at Tyndall National Institute. She received her MSc in Electronics and Telecommunications from Wroclaw University of Technology (2011) and her PhD in Applied Physics and Instrumentation from Cork Institute of Technology (2016). After joining Prof. Stefan Andersson-Engels’ Biophotonics@Tyndall group in 2017, she worked on optics-based surgical guidance and tissue imaging using upconverting nanoparticles. Between 2021 and 2023, she was a senior R&D biophotonics engineer at Rockley Photonics, developing silicon-photonics-based wearable sensors for health care monitoring. She now leads a sub-team at Tyndall advancing multimodal spectroscopy for diagnostic and surgical guidance applications in collaboration with clinicians and industry.

Venue

Room G06, Kane Science Building, UCC

Time/Date 

4pm / Monday, 17 Nov, 2025

Title

Light Matters: Exploring Light-Tissue Interactions for Biophotonic Applications

Abstract

Light provides a uniquely rich window into biology and medicine, enabling us to visualise and sense physiological processes in real time. This talk will present an overview of our research in biophotonics, spanning from translational optical diagnostics to fundamental studies of light–matter interactions in nanomaterials. I will introduce work ranging from diffuse reflectance spectroscopy and fluorescence lifetime imaging to emerging approaches that integrate machine learning for diagnostic insights. The main focus will be on our investigations of upconverting nanoparticles—exploring their nonlinear optical behavior, energy transfer dynamics, and potential for deep-tissue imaging and optical diagnostics. Together, these studies bridge applied biomedical optics and fundamental photo-physics, advancing the quantitative and technological frontiers of biophotonics.

Seminar Speaker

Dr Javier Porte Parera

Venue

Room G06, Kane Science Building, UCC

Time/Date 

4pm / Monday, 10 Nov, 2025

Title

Photonic Extreme Learning Machines based on Chip-Scale Chaotic Microresonators.

Abstract

In recent years, there has been a surge in the demand for machine learning and artificial intelligence systems with the list of applications ever increasing. Photonic integrated circuits (PICs) are a promising platform for implementing hardware-based neural networks because of their compact size, low power consumption and scalability. A particularly well suited computing architecture for PICs are extreme learning machines (ELMs). In photonic ELMs, a feed-forward randomly interconnected neural network expands the input information’s dimensionality and approximates complex classification tasks with only training the readout connections. Here, I review the state of the art in photonic ELMs and I introduce a photonic integrated implementation based on polymer chaotic microresonators. 

Seminar Speaker

Prof. Jerry Moloney 

Venue

Room G06, Kane Science Building, UCC

Time/Date 

4pm / Monday, 13 Oct, 2025

Title

Microscopic Physics Driven Design of 3D and Quasi-2D Semiconducting Materials.
 

Abstract

In this talk, I will describe how a systematic inclusion of Hartree-Fock field and energy
renormalization terms together with higher order correlations, account for all
microscopic processes involved in light-semiconductor interactions. The theory will be
shown to provide a one-to-one agreement with gain measurements across many
classes of semiconductor quantum well materials and establishes the limitations of the
famous ABC laws that phenomenologically account respectively for defect,
spontaneous emission radiative and Auger losses. My talk will include examples of
experiments on a broad class semiconductor disk lasers where the microscopic theory
was used to design a host of novel CW and mode-locked laser sources with
applications to compact extreme UV, room temperature tunable THz, artificial Guidestar,
offset-free mid-IR frequency comb and angle tunable multi-wavelength sources.
Recently, the theory was extended to a novel class of quasi-2D Transition Metal
Dichalcogenide (TMDC) materials that exhibit huge hundreds of meV bandgap
renormalization and haveprominent room temperature excitonic features.  Recent high field
physics applications include many-body enhancement of high harmonic generation in
these materials with plans to extend to topologically nontrivial materials.

Seminar Speaker

Dr Lewis Prole

Venue

Room G06, Kane Science Building, UCC

Time/Date 

4pm / Monday, 29 Sept, 2025

Title

Astrophysical versus Primordial Black Holes 

Abstract

The recent discovery that supermassive black holes (SMBHs) exist in the very early Universe has caused tensions with the Standard Cosmological Model, as theorists have struggled to explain how these objects became so massive in such a short period of time. This seminar will discuss current attempts to model SMBHs formation through astrophysical processes (such as star formation and direct collapse black holes), before considering the exotic possibility that some/all of what we call 'dark matter' is actually made up of primordial black holes (PBHs) which have existed since the time of the big bang.

Seminar Speaker

Gerard Higgins

Venue

Room G06, Kane Science Building, UCC

Time/Date 

4pm / Monday, 15 Sept, 2025

Title

Hunting for Dark Matter using Levitated Superconductors

Abstract

Recent advances in precision measurements with mechanical oscillators are enabling new tests of fundamental physics. They allow quantum physics to be probed using relatively large masses, and they open new avenues for dark matter detection. We are developing ultrasensitive mechanical sensors based on magnetically levitated superconductors. This platform is promising because the motion of the millimetre-scale superconductors can be (i) precisely probed using superconducting quantum circuits and (ii) highly isolated from environmental noise, thanks to levitation in near-dissipationless traps, under ultrahigh vacuum, at millikelvin temperatures.

Our sensors will probe a range of dark matter models in unexplored parameter regimes. With continued progress, our platform may enable a gravity-based search for dark matter in the laboratory, offering an exciting new avenue for discovery.

Seminar Speaker

Matthew Hopkins 

Venue

Room G06, Kane Science Building, UCC

Time/Date 

4pm / Monday, 8 Sept, 2025

Title

The Galactic Interstellar Object Population 

Abstract

Sourced from distant planetary systems and forming a huge Galaxy-spanning population, the properties of interstellar objects (ISOs) depend on processes across a range of astrophysical scales. This population plays an active role in Galactic life, potentially seeding planet formation in protoplanetary disks and causing fast radio bursts in collisions with neutron stars. With the imminent Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) set to increase our sample of known ISOs by an order of magnitude, I will present a predicted chemodynamical model of the ISO population derived using the Gaia stellar survey and models of protoplanetary disk chemistry, along with a simulation of ISO discoveries in the LSST. I predict that the Galactic ISO population has a complex velocity distribution which is correlated with both chemical composition and age, and that these features will be retained in the sample discovered by the LSST. Furthermore, the discoverability simulation shows that the LSST will find 5-50 ISOs over 10 years, and constrain the size frequency distribution slope of ISOs with just a few discovered objects. These results mean that the Rubin ISO sample can be used to test models of planetesimal formation, Galactic evolution, and tidal stream formation.