The tri-partite project involving teams from Trinity college Dublin (Republic of Ireland), University of Virginia (USA), Virginia Tech University (USA) and Queen’s University Belfast aims to discover new ways to grow ferroelectric hafnia thin films which could be compatible with manufacturing processes. Ferroelectricity in hafnia films has triggered significant research interest over the past decade due to its immense promise for next-generation memory devices. However, the origin of ferroic behavior at the nanoscale and the means to control it remain an open question, with the consensus being that it deviates from conventional ferroelectrics.

This work investigates uncapped hafnia films and the critical role of the surrounding atmosphere in influencing their ferroelectric response. We demonstrate a reversible transition between non-ferroelectric and ferroelectric states by simply modulating environmental conditions, accompanied by a significant enhancement in piezoelectric response under controlled environments. Specifically, we systematically explored domain relaxation in a variety of atmospheres — ambient air, oxygen, nitrogen, and carbon dioxide — under both low and high humidity. These findings provide a compelling explanation for the widespread inconsistencies reported in the literature, revealing how these atmospheric conditions contribute to conflicting interpretations of ferroelectricity in hafnia-based systems.

Lead authors Dr. Waseem Wani and Prof. Brian Rodriguez (UCD) said: ‘We believe this research helps to bridge existing gaps in understanding the nanoscale ferroelectric response of hafnia films, addressing key doubts that have persisted in the community. These insights are not only valuable from a fundamental physics perspective, but also offer practical guidance for improving domain retention in memory devices. Given the electrochemical sensitivity of hafnia-based materials, our findings point toward practical steps to ensure long-term stability and performance improvements in real-world devices.’

Dr. Kristina Holsgrove and Dr. Amit Kumar who led the work on QUB front added: ‘With the growing importance of Hafnia in modern devices, the debate on the nature of ferroelectricity has indeed intensified. The insights from this work reveal a significant strategy for stabilizing ferroic responses by carefully regulating the chemical environment, offering new possibilities for precise control in hafnia-based films.’

The work has been published recently in the high-visibility journal Advanced Materials.