This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Carnegie Mellon University scientists have uncovered a new phenomenon that challenges a longstanding assumption about how electronic materials respond to magnetic fields. The discovery broadens the fundamental understanding of the Hall effect, a principle widely used to measure the magnetic and electronic properties of materials.
Published in Nature Materials, the research could lay the groundwork for simpler, more versatile magnetic sensing technologies used in electronics, transportation and medical imaging. The Hall effect has been a key tool for studying material properties for more than a century. In 1879, Edwin Hall showed that applying a magnetic field perpendicular to a material deflects moving charges, producing a measurable voltage.
By analyzing this signal, scientists can determine whether electric current is carried by negative or positive charges, how many of those charges are moving through the material and how easily they flow. Today, the Hall effect is integral to widely used sensing technologies found in systems ranging from automobiles to computer keyboards. In the latest work, researchers in Carnegie Mellon's Department of Physics, working in the Lab for Investigating Quantum Materials, Interfaces and Devices (LIQUID), identified a new form of the Hall effect.
"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," said Simranjeet Singh, an associate professor of physics. The discovery expands the role of the Hall effect as a core tool in physics because it allows for a magnetization-dependent Hall response in more than one direction.
This allows researchers to probe and understand multidimensional magnetic and topological configurations in condensed matter systems. "Beyond fundamental importance, this discovery can enable novel planar device architectures and sensor types, such as vector magnetometry, by measuring the out-of-plane and in-plane anomalous Hall effect signals in the same device," Singh said. The idea of an in-plane anomalous Hall effect was proposed theoretically but never experimentally demonstrated—until now.
"People proposed it and ideas were out there, but it's very difficult to make a magnetic material with the right symmetry to do it," Singh said. "What we did was we found a material with the right symmetry and we made it magnetic." To build the unique nanometer-sized devices used in this research, Singh turned to Jyoti Katoch, an associate professor of physics and an expert in fabricating devices from two-dimensional quantum materials. The team, including postdoctoral researchers I-Hsuan Kao and Ravi Kumar, started with tantalum iridium telluride (TaIrTe4), which has the necessary crystalline symmetry to produce a multidimensional Hall effect.
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