147 years after Hall Effect discovery, scientists find it works in-plane

Nearly 150 years after its initial discovery, scientists have demonstrated that the Hall effect can work in a plane rather than perpendicular to a material, as previously believed. Researchers at Carnegie Mellon University have developed an unusual form of the Hall effect in which a magnetic field within the plane of a material can generate a measurable Hall response.

This finding, published in Nature Materials, challenges the long-held assumption in condensed matter physics and could lead to simpler magnetic sensors capable of detecting fields in multiple directions. The Hall effect, first observed by Edwin Hall in 1879, occurs when a magnetic field pushes charges moving through a material, creating a voltage across the material that reveals information about the material's properties.

Traditional Hall-effect sensors have been used in various applications, including automobiles, keyboards, and industrial electronics. However, the new discovery shows that the Hall response does not have to be limited to the traditional geometry. The Carnegie Mellon researchers achieved this result by combining tantalum iridium telluride (TaIrTe₄), a two-dimensional quantum material, with chromium germanium telluride (Cr₂Ge₂Te₆), a magnetic material.

By reducing the TaIrTe₄ to a few atomic layers and placing it near the CGT, the researchers created an atomically thin device with unique electronic and magnetic properties. This combination reduces the system's symmetry and enables additional spin-orbit coupling at their interface, which becomes significant when CGT becomes ferromagnetic at low temperatures, resulting in the in-plane anomalous Hall response.

The researchers believe that this discovery could lead to new forms of vector magnetometry, with applications in electronics, transportation, and medical imaging.