Hydrogen Ions Manipulate Weyl Nodes in Magnetic Topological Material

A team of physicists led by Lia Krusin-Elbaum from The City College of New York has developed a groundbreaking technique that utilizes hydrogen cations (H+) to manipulate the electronic band structures in a magnetic Weyl semimetal—a type of topological material in which electrons behave like massless particles called Weyl fermions. These fermions are unique because of their “chirality” or “handedness,” which is intrinsically linked to the spin and momentum of the particles. This discovery opens up new possibilities for quantum devices and offers a deeper understanding of the interplay between topological materials, spintronics, and quantum computing.

The material at the heart of this research is MnSb₂Te₄, a magnetic Weyl semimetal. By introducing hydrogen ions into this material, the team was able to tune the chirality of the electronic transport properties, essentially reshaping the energy landscapes known as Weyl nodes within the material. This tunability is a remarkable feature, as it allows for the on-demand manipulation of the material’s topological properties, which could lead to new quantum devices that capitalize on these emergent states.

The results of this study were published in the journal Nature Communications, under the title “Transport chirality generated by a tunable tilt of Weyl nodes in a van der Waals topological magnet.” This work not only demonstrates the potential for creating chiral currents with low dissipation but also contributes to the field by showing how the introduction of hydrogen ions can enhance and stabilize the material’s chiral properties.

When hydrogen ions are introduced into MnSb₂Te₄, they repair the disorder in the Mn-Te bonds, which reduces scattering between the Weyl nodes, leading to improved electronic transport. The team observed that the electrical charges in the material move differently depending on the direction of the in-plane magnetic field, which can be rotated clockwise or counterclockwise. This directional behavior results in low-dissipation currents, a desirable characteristic for many quantum devices. These currents are not just efficient but are also associated with a phenomenon called the “angular transport chirality,” which is strongly correlated with a rare, field-antisymmetric longitudinal resistance. This allows for a low-field tunable “chiral switch,” a feature that is based on the complex interplay between topological Berry curvature, the chiral anomaly, and the hydrogen-modulated Weyl nodes.

One of the most exciting aspects of this research is the tunability of the material’s topological properties. The introduction of hydrogen ions leads to a doubling of the Curie temperature—an important parameter that governs the magnetic properties of the material—allowing the system to maintain its topological character at higher temperatures. The result is a material that can be fine-tuned to exhibit desirable quantum properties, making it an attractive candidate for use in future quantum devices. According to Krusin-Elbaum, this study represents a significant step forward in expanding the scope of topological quantum materials. By using hydrogen and other light elements to modify the band structures of these materials, researchers can create designer quantum systems that go beyond what is naturally found in nature, opening up new possibilities for applications in fields like quantum computing and nano-spintronics.

The technique demonstrated in this study is not limited to the specific material MnSb₂Te₄ but is considered to be generalizable, meaning it could be applied to a wide range of topological materials. This versatility increases the potential for using topological quantum materials in various technological platforms, from energy-efficient electronics to advanced quantum systems. Krusin-Elbaum and her team have emphasized that this work could significantly advance the development of quantum electronics by providing a new way to manipulate the fundamental properties of materials at the atomic level.

The research is part of the broader efforts at the Harlem Center for Quantum Materials, a collaborative initiative at City College that focuses on solving fundamental challenges related to novel materials systems with immense scientific and technological potential. The center’s goal is to explore how these materials can be used in future technologies, particularly those related to energy efficiency and quantum computing.

In addition to the fundamental science involved in this study, there are practical implications for the potential industrialization of these techniques. If successfully harnessed, the ability to manipulate the electronic and magnetic properties of topological materials at the atomic level could lead to more efficient quantum devices, including fault-tolerant quantum computers, advanced sensors, and energy-efficient electronic systems.

The research has been supported in part by the National Science Foundation, which plays a crucial role in funding transformative scientific advancements. The funding and collaboration between academic institutions and governmental agencies are essential in advancing the field of quantum materials, as the applications of these materials have the potential to revolutionize entire industries.

Ultimately, this work demonstrates that we are on the cusp of a new era in materials science, where topological properties can be engineered and controlled for practical applications. The ability to tune materials like MnSb₂Te₄ to exhibit specific quantum behaviors is a significant step toward realizing the potential of quantum technologies. As the field progresses, we can expect to see even more innovative breakthroughs that could lead to faster, more efficient, and more powerful quantum devices, all rooted in the study of topological materials and their unique properties.

Reference: Afrin N. Tamanna et al, Transport chirality generated by a tunable tilt of Weyl nodes in a van der Waals topological magnet, Nature Communications (2024). DOI: 10.1038/s41467-024-53319-w