Researchers at Carnegie Mellon University have overturned a 147-year-old physics assumption by demonstrating that the Hall effect can operate with an in-plane magnetic field rather than strictly requiring a perpendicular orientation. Published in Nature Materials, this discovery breaks a foundational principle established in 1879, opening pathways for multidimensional magnetic sensors in consumer electronics, automotive systems, and medical imaging.
Rewriting a Foundational Principle from 1879
Edwin Hall discovered in 1879 that applying a magnetic field perpendicular to a current-carrying material pushes moving charges to one side. This generates a measurable transverse voltage. For over a century, physicists relied on this exact perpendicular configuration to determine whether charge carriers are positive or negative, count their density, and measure their mobility. Hall effect sensors quickly became ubiquitous hardware components, embedded everywhere from computer keyboards to vehicles.
That rigid rulebook just expired. Working inside the Lab for Investigating Quantum Materials, Interfaces and Devices (LIQUID), researchers demonstrated an unconventional magnetic response that defies standard textbooks. Simranjeet Singh, an associate professor of physics at Carnegie Mellon, noted that while theorists previously predicted an in-plane anomalous Hall effect, experimental proof remained elusive until now.
“For a long time, people thought the Hall effect only worked when the magnetic field was applied perpendicular to the plane of the film. We’ve shown that that’s not true — you can also get a response when the field is in-plane,” Singh stated.
Engineering Atomic Heterostructures for Multidimensional Sensing
Proving the theory required materials possessing specific crystal symmetries combined with precise nanoscale engineering. Singh collaborated with Jyoti Katoch, an associate professor of physics specializing in two-dimensional quantum material fabrication, alongside postdoctoral researchers I-Hsuan Kao and Ravi Kumar.
The team constructed atomically thin devices using tantalum iridium telluride (TaIrTe4), a material possessing the crystal symmetry required to support a multidimensional Hall response. They reduced this material down to just a few atomic layers in thickness, layering it directly against a magnetic substrate layer composed of chromium germanium telluride (CGT).
Proximity is everything here. Because the TaIrTe4 sits directly adjacent to the CGT layer, the magnetic behavior of the CGT bleeds into the normally nonmagnetic TaIrTe4. This induces localized magnetic properties while preserving the host material’s inherent electronic transport characteristics. “This truly demonstrates the power of building atomically precise heterostructures of emergent two-dimensional quantum materials to obtain on-demand electronic and magnetic properties,” Katoch explained.
Real-World Hardware Implications and Vector Magnetometry
Detecting both the standard transverse signal and a secondary, unconventional signal associated with in-plane magnetization within a single ultrathin device changes engineering parameters for hardware designers. Traditional magnetometer setups require multiple discrete sensors oriented across different axes to map complex magnetic vectors. This discovery eliminates that redundancy.
A single device can now capture out-of-plane and in-plane anomalous Hall effect signals simultaneously. This capability paves the way for vector magnetometry architectures that streamline component footprints in tight electronic spaces.
“You can do multi-axis sensing with a single, highly compact device,” Singh explained regarding the practical scope of the work. The team is currently investigating alternative material combinations and testing device functionality at room temperature, marking a critical transition from quantum lab instrumentation toward scalable commercial manufacturing.
