Karthika Kariattukarakaran
What inspired you to pursue this research topic, and how has your understanding of it evolved throughout your PhD journey?
I did my Master’s thesis on magnetic materials, particularly multiferroics, where I investigated structure-property relationships using X-ray diffraction and macroscopic magnetization measurements. This experience first sparked my curiosity about how atomic arrangements give rise to complex magnetic behavior. During my PhD, I was able to expand this interest by studying a variety of metallic alloy systems, including magnetic quasicrystal approximants and alloys relevant for magnetocaloric applications, such as Fe₂P-based and Re₂In systems. Here, my focus shifted toward using neutron scattering as a primary tool. Neutrons allowed me to probe magnetic properties on the microscopic level, specifically the arrangement of spins and how these evolve with changes in composition or structural parameters. Over time, my understanding has developed from exploring general correlations between structure and magnetism to uncovering detailed magnetic structures and their implications for energy-related applications.
Can you describe a key finding or insight from your research that you’re especially proud of—and why it matters in your field?
One of the findings I am most proud of is the work on Fe₂P-based compounds, which are considered promising materials for magnetic refrigeration. By studying how substituting Fe₂P with Mn and Si affects its structure and magnetism, it was shown how subtle changes in composition can drastically alter magnetic ordering.
In its pure form, Fe₂P has magnetic moments aligned along the c-axis. With low Mn substitution, however, the system transforms into an incommensurate magnetic structure, meaning the magnetic ordering no longer matches neatly with the underlying crystal lattice. This unusual state reflects a complex interplay between structure and magnetism. At higher Mn concentrations, the system simplifies again into a ferromagnetic arrangement.
This insight is important because it demonstrates how tuning composition can directly influence magnetic structures, and in turn, magnetocaloric properties. Such understanding provides a pathway for designing next-generation materials for energy-efficient cooling technologies, helping to bring magnetic refrigeration closer to practical applications.
How do you hope your research will be used or built upon after your defense—whether in academia, industry, or society at large?
I hope my research will serve as a foundation for both fundamental studies and applied work in the future. By focusing on structure-property relationships in different intermetallic systems, my findings can be extended to explore other materials with potential for energy-related applications or to deepen our understanding of complex magnetic behavior.
For example, my work on magnetic quasicrystal approximants contributes primarily to fundamental science, since these structurally complex systems often host unusual or exotic magnetic states. Insights from such studies can help guide the investigation of other materials with non-trivial magnetic order. On the other hand, my research on Fe₂P-based systems is much more application-driven. These compounds show promise as magnetocaloric materials, which could be used in magnetic refrigeration technology. This has significant societal value, as it offers a sustainable and environmentally friendly alternative to conventional cooling methods, with the potential to reduce energy consumption and greenhouse gas emissions. In this way, I see my research bridging both fundamental curiosity and practical solutions.
What role has SwedNess played in your journey?
SwedNess has played a central role in my PhD journey. Neutron scattering was the key technique in my research, and gaining access to large-scale facilities would not have been possible without the financial and logistical support that SwedNess provides. Equally important was the community. Through SwedNess, I was able to connect with fellow PhD students who also use neutrons, though often in very different ways. I was also able to perform an extended stay at ISIS, pulsed neutron and muon source in the UK. That stay allowed me to complete two of my important PhD projects while also building connections with leading experts in neutron diffraction.
