Quantum materials are distinguished by their unique and often exotic responses to external stimuli such as magnetic fields, temperature variations, and electromagnetic radiation. Phenomena like superconductivity, where electrical resistance vanishes, spontaneous magnetic ordering without external influence, and charge density waves emerge from the delicately balanced interactions between electrons and atomic lattices. These phenomena have intrigued the scientific community, pushing the boundaries of understanding in condensed matter physics and inspiring the exploration of yet unknown novel effects that may underpin next-generation technologies.

Central to comprehending these complex behaviors is the profound understanding of electron dynamics within these solids. Electrons in quantum materials do not behave as isolated particles but exhibit collective phenomena, resulting in macroscopic physical properties that can be dramatically altered by minute changes in electronic distribution. This distribution serves as a fundamental “fingerprint” of each material, encoding its quantum mechanical characteristics. By mastering the manipulation of these electronic fingerprints, scientists aim to tailor materials with desired functionalities, offering unprecedented control over electronic, magnetic, and optical properties for innovative device applications.

Professor Fedchenko’s approach leverages sophisticated photon-based techniques to probe the electronic landscapes of quantum materials. Utilizing a spectrum of photon sources, including laser light, high-energy X-rays, and traditional discharge lamps, her experimental setups facilitate the ejection of electrons from a material’s surface through the photoelectric effect. The kinetic energy and angular distribution of these emitted electrons provide direct insight into the momentum and energy configurations of electrons inside the material, thus revealing its internal quantum structure and interactions.

A key instrument in her experimental arsenal is angle-resolved photoemission spectroscopy (ARPES), enhanced by state-of-the-art time-of-flight electron detection. This technique not only captures the energy but also the momentum distribution of photoemitted electrons with exceptional precision and timing resolution, enabling a direct mapping of the electronic band structure. The detailed spectral information obtained through ARPES informs on how electrons pair, scatter, or localize—critical factors underpinning quantum phenomena such as high-temperature superconductivity and topological states of matter.

Researching these frontier materials requires not only cutting-edge instrumentation but also interdisciplinary collaboration across experimental and theoretical physics. Professor Fedchenko’s work bridges these domains, correlating empirical data with quantum mechanical models to deepen the fundamental understanding of strongly correlated electron systems. This synergy is vital for decoding the complex interplay between electronic correlations and lattice dynamics that govern the emergent properties observed in novel quantum states.

The establishment of the Gisela and Wilfried Eckhardt Endowed Professorship for Experimental Physics at Goethe University Frankfurt, proudly held by Professor Fedchenko, marks a significant milestone in institutional support for quantum materials science. This prestigious position, generously funded by the Volkswagen Foundation and the legacy of alumna Gisela Eckhardt, affords the resources necessary to pursue ambitious experimental programs, fostering innovation at the intersection of solid-state physics and materials engineering.

Professor Fedchenko’s academic journey is emblematic of exceptional international scholarship and scientific contribution. Originating from Ukraine, she earned her doctorate in physics and mathematics before advancing to research roles that shaped her expertise in photoemission spectroscopy at prominent institutions, including Johannes Gutenberg University Mainz and DESY in Hamburg. Her trajectory exemplifies the global collaboration and dedication propelling quantum materials research forward.

Her inventive spirit is further exemplified by her co-holding of a patent with French collaborators for a novel pulsed electron source and surface analysis system. This technology harnesses a cold atom trap to produce a monochromatic, high-resolution pulsed photon beam, enabling unprecedented surface studies of complex materials. Such advancements are critical to pushing the frontiers of surface science and electron spectroscopy.

The implications of Professor Fedchenko’s research extend well beyond academic curiosity. Quantum materials hold the key to transformative technologies—from quantum computers that exploit electron coherence to sensors with sensitivity beyond classical limits, and solar cells enhanced by quantum effects for superior energy conversion efficiencies. The comprehensive understanding gleaned through her photoemission spectroscopy work is foundational to harnessing these capabilities.

Colleagues and university leadership acknowledge the profound impact of this research direction. President Enrico Schleiff underscores the strategic importance of this professorship in enriching collaboration within the Rhine-Main Universities alliance and securing momentum in quantum materials innovation amid shrinking academic funding landscapes. Simultaneously, the Volkswagen Foundation’s Dr. Georg Schütte highlights the critical role of sustained investment in complex basic science infrastructure and the successful culmination of their flagship Lichtenberg Program.

Ultimately, the integration of advanced experimental physics techniques with rigorous theoretical frameworks under Professor Fedchenko’s leadership is poised to yield transformative insights into the quantum world. These revelations will pave the way for rational design and controlled manipulation of quantum materials, heralding a new era of innovative devices that capitalize on their extraordinary macroscopic properties born from the quantum realm.

As this vibrant research community moves forward, the foundational understanding of electron behavior in quantum materials will remain at the heart of unlocking future technologies capable of addressing the pressing challenges of computing power, sensing precision, and energy sustainability in the 21st century.

Subject of Research:
Quantum materials; electronic structure; angle-resolved photoemission spectroscopy; experimental solid-state physics; photoelectric effect; quantum phenomena in materials.

Article Title:
Unveiling the Quantum Frontier: Professor Olena Fedchenko’s Pioneering Insights into the Electronic Structures of Quantum Materials

News Publication Date:
2025

Image Credits:
Ekaterina Fedorenko / Goethe University Frankfurt

Keywords

Quantum mechanics, Quantum materials, Quantum measurement, Quantum states, Quantum tunneling, Photoemission spectroscopy, Experimental physics, Solid-state physics, Condensed matter physics, Photonics, Electron spectroscopy, Quantum phenomena

Piezoelectric materials, known for their ability to generate electric charges in response to mechanical deformation and, conversely, to change shape when subjected to an electric field, underpin a myriad of everyday applications. These include audio devices such as microphones, speakers, and headphones, where they translate sound vibrations into electrical signals and vice versa. However, the most effective piezoelectric materials historically contain lead, a toxic element posing significant environmental hazards.

Recognizing the urgent need to develop lead-free alternatives without sacrificing performance, the Osaka Metropolitan team concentrated on bismuth ferrite (BiFeO3), a promising non-toxic candidate. Despite its environmental benefits, bismuth ferrite’s practical deployment has been hindered by substantial electrical leakage and suboptimal piezoelectric efficiency. Such limitations have restricted its utility in functional devices, motivating researchers to seek innovative solutions to enhance its properties.

The team achieved a major breakthrough by doping bismuth ferrite with manganese, creating an ultrathin epitaxial film grown directly on silicon. Unlike the desirable compressive strain that typically enhances piezoelectric behavior, the lattice mismatch between bismuth ferrite and the silicon substrate induces tensile strain, which historically degrades material performance by pulling the film apart during cooling. Instead of circumventing this tensile strain, the researchers ingeniously leveraged it to induce a structural phase transition within the crystal lattice, transforming it from its natural rhombohedral configuration to a monoclinic phase.

This strain-induced phase transition profoundly affects the atomic arrangement, optimizing the electromechanical coupling essential for piezoelectric performance. By harnessing tensile strain to manipulate crystal symmetry, the team unlocked enhanced piezoelectric responses that surpass previous reports for bismuth ferrite films. This novel approach not only raises the functionality of the material but also demonstrates the critical role of strain engineering in tuning complex oxide thin films for advanced device applications.

Developing these films required overcoming formidable technical challenges, most notably the low melting point of bismuth, which makes the film composition extraordinarily sensitive to growth temperature. Traditional fabrication techniques fell short in controlling these parameters with sufficient precision. To address this, the researchers devised a unique “biaxial combinatorial sputtering” method. This technique allows continuous variation of growth temperature and chemical composition across a single silicon wafer, expediting the optimization process by simultaneously exploring myriad deposition conditions.

Employing this innovative sputtering approach enabled the rapid identification of optimal parameters where tensile strain effectively triggers the desirable phase transition. The resulting manganese-doped bismuth ferrite films exhibit the highest piezoelectric response measured to date for this material system, confirming the efficacy of strain engineering combined with precise compositional control. This synergy paves the way for high-efficiency, environmentally benign piezoelectric devices compatible with industrial semiconductor processes.

The practical applicability of these films was validated by integrating them into microelectromechanical systems (MEMS) vibration energy harvesters, devices that convert mechanical vibrations into usable electrical energy—a vital technology for powering autonomous sensors and Internet-of-Things devices. Testing revealed a dramatic fivefold improvement in energy conversion efficiency compared to traditional bismuth ferrite harvesters. Furthermore, the devices demonstrated robust performance under both continuous vibrations and sudden impacts, mimicking real-world operating conditions such as those encountered in industrial machinery or mobile electronics.

Crucially, the use of sputtering deposition on standard silicon wafers ensures that this technology can be scaled for industrial manufacturing, obviating the need for exotic substrates or complex fabrication routes. The compatibility with conventional semiconductor workflows accelerates the potential translation from laboratory research to commercial products, heralding a new era of sustainable, high-performance piezoelectric electronics.

The implications of this study extend far beyond academic interest, offering a tangible pathway to reduce reliance on hazardous lead-based materials in electronic components. As industries worldwide increasingly prioritize environmental stewardship, the integration of lead-free, high-efficiency piezoelectric materials into ubiquitous technologies holds promise for mitigating the ecological impact of future electronics, fostering safer and greener consumer and industrial products.

Looking ahead, the research team aspires to broaden the application spectrum of these advanced films to include smart sensors and self-powered devices, vital elements for the growing ecosystem of interconnected, low-maintenance electronics. Harnessing vibration energy harvesting with improved material performance could revolutionize energy autonomy in miniaturized electronic systems, addressing the pressing challenges posed by limited battery lifespans and environmental waste.

This innovative work exemplifies the power of combining materials science, semiconductor engineering, and creative methodological advances to address pressing societal needs. By transcending fundamental limitations through strain engineering and precision sputtering, the Osaka Metropolitan University researchers have opened new frontiers in piezoelectric MEMS devices, marrying ecological responsibility with cutting-edge technological performance.

In sum, the ability to fabricate manganese-doped bismuth ferrite ultrathin films exhibiting superior piezoelectric performance directly on silicon wafers marks a pivotal advancement toward sustainable, lead-free electronics. As these materials transition from experimental validation to widespread manufacturing, they hold promise to transform the landscape of energy harvesting technology and foster a greener electronics industry.

Subject of Research: Not applicable

Article Title: Enhanced Electromechanical Coupling in Piezoelectric MEMS Vibration Energy Harvesters via Strain-induced Phase Transition in Mn-doped Bismuth Ferrite Epitaxial Films

News Publication Date: 17-Mar-2026

Web References:
https://www.omu.ac.jp/en/
http://dx.doi.org/10.1038/s41378-026-01177-5

References:
Yoshimura, T. et al. Enhanced Electromechanical Coupling in Piezoelectric MEMS Vibration Energy Harvesters via Strain-induced Phase Transition in Mn-doped Bismuth Ferrite Epitaxial Films. Microsystems & Nanoengineering (2026). DOI: 10.1038/s41378-026-01177-5

Image Credits: Osaka Metropolitan University

Keywords

Lead-free piezoelectric materials, manganese-doped bismuth ferrite, strain engineering, phase transition, vibration energy harvesting, MEMS devices, sputtering technique, silicon wafers, electromechanical coupling, sustainable electronics, energy conversion efficiency, microelectromechanical systems