In-plane magnetic fields reveal new Hall-effect behaviors in advanced materials

In-plane magnetic fields are responsible for inducing an anomalous Hall effect in EuCd₂Sb₂ films, report researchers at the Tokyo Institute of Science. By studying how these fields modify electronic structures, the team discovered a large anomalous Hall effect in the plane.

These results, published in Physical Examination Letters on December 3, 2024, will pave the way for new strategies for controlling electronic transport under magnetic fields, potentially advancing applications in magnetic sensors.

The Hall effect is a fundamental phenomenon in materials science. This occurs when a material carrying an electric current is exposed to a magnetic field, producing a voltage perpendicular to both the current and the magnetic field. This effect has been widely studied in materials subjected to out-of-plane magnetic fields. However, research into how in-plane magnetic fields induce this phenomenon is very limited.

In recent years, in-plane magnetic fields have attracted increasing interest due to their potential to unlock new material behaviors, particularly in materials with singular points in their electronic band structures, such as EuCd.₂Sb₂.

In this context, a team of researchers from the Tokyo Institute of Science and the RIKEN Center for Emerging Materials Science (CEMS), led by Associate Professor Masaki Uchida, explored how in-plane magnetic fields induce the anomalous Hall effect in EuCd.₂Sb₂ movies. Their study sheds light on how these fields induce a distinctive change in electronic band structures.

Uchida explains: “Our findings highlight a new way to manipulate the Hall effect in magnetic materials. This opens exciting possibilities for future technologies that rely on precise measurement of the magnetic field, such as magnetic sensing.”

The team’s efforts revealed that in-plane magnetic fields lead to a significantly large anomalous Hall effect in EuCd.₂Sb₂ thin films. This effect changes sign with the rotation of the in-plane magnetic field, exhibiting a clear threefold symmetry for the rotation of the in-plane magnetic fields.

Furthermore, the study revealed that these effects are linked to an unusual out-of-plane shift of singular points in the electronic band structures. This movement corresponds to the manifestation of orbital magnetization, which is the rotational movement of an electronic wave packet, formulated in modern terms as a quantum geometric tensor in solids.

This discovery deepens our understanding of how in-plane magnetic fields change the internal structure of the material.

The researchers also found that even small adjustments in the angle of the magnetic field could lead to significant variations in the in-plane anomalous Hall effect. This directional dependence highlights the versatility of the material and its potential for use in technologies requiring precise measurement of magnetic fields in specific directions.

Uchida concludes: “The present work not only heralds a breakthrough in the experimental study of orbital magnetization, but also stimulates the development of materials for future applications, revolutionizing the concept of the ‘outside-in’ Hall effect. interior”.

Overall, this study improves our understanding of how in-plane magnetic fields influence the electronic properties of advanced materials, such as EuCd.₂Sb₂bringing us closer to the development of materials with magnetotransport properties suitable for future technologies.