Physicists have uncovered an in-plane Hall response that overturns a century-old assumption about how this famous electrical effect works. The discovery could eventually make multidirectional magnetic sensing possible with one tiny device.
Scientists at Carnegie Mellon University have identified an unexpected form of the Hall effect that challenges a long-standing assumption about how electronic materials react to magnetic fields.
The finding expands scientists’ understanding of the Hall effect, a fundamental phenomenon used to study the electrical and magnetic properties of materials.
Published in Nature Materials, the work could eventually help researchers develop simpler and more flexible magnetic sensors for applications including electronics, transportation, and medical imaging.
A Century-Old Physics Effect
The Hall effect has been an important tool in physics for more than a century. In 1879, Edwin Hall discovered that when a magnetic field is applied perpendicular to a material carrying an electric current, the moving charges inside are deflected, creating a measurable voltage.
That signal can reveal several important properties of a material. Scientists can use it to determine whether current is being carried by negative or positive charges, estimate how many charge carriers are moving through the material, and measure how easily they travel.
Today, Hall effect sensing is widely used in technologies ranging from automobiles to computer keyboards.
Researchers in Carnegie Mellon’s Department of Physics, working in the Lab for Investigating Quantum Materials, Interfaces and Devices (LIQUID), have now demonstrated a previously unconfirmed form of the 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.
Detecting Magnetism in More Than One Direction
The discovery broadens how the Hall effect can be used because it shows that a magnetization-dependent Hall response can occur in more than one direction.
That capability could help physicists study complicated magnetic and topological structures in condensed matter systems. In simple terms, researchers may be able to use the same basic phenomenon to probe how magnetism behaves along multiple directions inside advanced materials.
“Beyond fundamental importance, this discovery can enable novel planar device architectures and sensor types, such as vector magnetometry, via measuring the out-of-plane and in-plane anomalous Hall effect signals in the same device,” Singh said.
From Theory to Experimental Proof
Scientists had previously proposed the possibility of an in-plane anomalous Hall effect, but no experiment had successfully demonstrated it.
“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 create the tiny devices needed for the study, Singh worked with Jyoti Katoch, an associate professor of physics who specializes in fabricating devices from two-dimensional quantum materials.
The research team, which also included postdoctoral researchers I-Hsuan Kao and Ravi Kumar, began with tantalum iridium telluride (TaIrTe4). This material has the crystalline symmetry needed to produce a multidimensional Hall effect.
The researchers reduced it to only a few atomic layers in thickness and then paired it with a magnetic layer, Cr2Ge2Te6 (CGT).
Because the two materials sit extremely close together, magnetism from the magnetic layer can influence the normally nonmagnetic layer. This gives the TaIrTe4 magnetic properties while allowing it to retain its distinctive electronic behavior.
“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 said.
One Tiny Device, Multiple Magnetic Axes
Inside the atomically thin devices, the researchers detected both the conventional Hall signal and a second, unconventional signal tied to magnetization within the plane of the material.
Practically, that means a single ultrathin device can detect magnetic fields along more than one axis.
“We have broadened the potential application of these materials,” Singh said. “You can do multidimensional magnetic sensing with one sensor only. Before, you needed to put two sensors to measure the magnetic field in two directions.”
The result could eventually simplify certain magnetic sensing systems by allowing one device to perform measurements that previously required multiple sensors.
Explaining the Unusual Hall Response
To understand why the new effect appears, Shubhayu Chatterjee, an assistant professor of physics, performed theoretical modeling.
His work focused on how the symmetry of the combined materials changes when TaIrTe4 is paired with CGT, and how those changes allow the unusual Hall response to emerge.
“We found that the reduced symmetry due to pairing with CGT allows additional spin-orbit coupling at the interface. These spin-orbit coupling terms are crucial for the in-plane anomalous Hall effect to emerge once CGT becomes ferromagnetic at low temperatures. While certain features of the observed anomalous Hall effect signal are consistent with an intrinsic origin, a detailed characterization of few-layered TaIrTe4 is needed to nail down the precise mechanism,” Chatterjee said.
Spin-orbit coupling describes an interaction between an electron’s motion and its quantum spin. In this case, the interface between the two materials appears to create the conditions needed for the unusual in-plane Hall response.
Toward Practical Magnetic Sensors
The LIQUID team is now investigating other material combinations that might produce the same unconventional Hall behavior.
Researchers are also testing how the device performs at room temperature. Demonstrating a strong room-temperature response would be an important step toward turning the phenomenon into practical sensing technology.
Reference: “In-plane anomalous Hall effect in a low-dimensional system” by I-Hsuan Kao, Ravi Kumar Bandapelli, Zhenhong Cui, Shuchen Zhang, Jian Tang, Tiema Qian, Souvik Sasmal, Aalok Tiwari, Mei-Tung Chen, Raghvendra Posti, Rahul Rao, Jiahan Li, James H. Edgar, Kenji Watanabe, Takashi Taniguchi, Ni Ni, Su-Yang Xu, Qiong Ma, Shubhayu Chatterjee, Jyoti Katoch and Simranjeet Singh, 28 May 2026, Nature Materials.
DOI: 10.1038/s41563-026-02611-9
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3 Comments
Physicists have uncovered an in-plane Hall response that overturns a century-old assumption about how this famous electrical effect works. The discovery could eventually make multidirectional magnetic sensing possible with one tiny device.
VERY GOOD.
May I ask physicists:
1. Are the various assumptions in mainstream physics scientific?
2. Are you uncovering a assumption or a methodological flaw?
Today’s mainstream physics has long been mired in pseudoscience and has systematically lost its ability to correct errors.
For example：
A Tale of Officialdom in Contemporary Physics — A Gift for International Children’s Day (2024)
Please enjoy four volumes of “A Hundred Schools in Shattered Drama,” in the spirit of “Let a hundred flowers bloom, a hundred schools of thought contend.”
Volume I: The Dream
Warm sunlight bathed the North American continent. PRL, wearing gold-rimmed reading glasses, turned the pages of journals it had once published, one by one, with aged and trembling fingers, savoring every page with quiet delight.
Just then, two children stumbled into the room, rubbing their sleepy eyes, and threw themselves against PRL’s legs, shaking them with all their might. PRL removed his reading glasses, lowered his head, and gazed down at the two innocent children with a kindly expression — and a face full of puzzlement.
The two children (with a look of haughty pride, gazing up at Grandpa PRL):
Grandpa! Grandpa! We just had a dream — we dreamed that two sets of Cobalt-60, spinning in opposite directions, could transform into two objects that are mirror images of each other.
PRL (waving his hand, seemingly a little annoyed):
Preposterous! Grandpa has never seen two physical objects become mirror images of each other simply by spinning in opposite directions.
The two children (looking straight into Grandpa PRL’s eyes, utterly serious):
Grandpa! You must believe us — it really is true. We have dreamed of this strange physical phenomenon again and again, and verified it many times over.
Old Grandpa PRL slowly raised his head and gazed out the window, lost in thought.
In the azure sky, two white clouds drifted lazily. A few little birds had gathered on a rotting dead branch among the trees, chirping away at the clouds.
PRL (tapping his forehead lightly with all ten fingers, struggling to recall):
Perhaps Grandpa really is getting old. Isn’t this exactly the dream Grandpa used to have when he was a child?
PRL (sinking into deep thought). After who knows how long, he raised his head with resolve.
PRL (gently stroking the two children’s heads, his heart surging with emotion):
Good children! Seeing you reminds Grandpa of what he was like as a boy. Grandpa believes you. Right now, Grandpa will make your dream come true and announce this tremendous news to the world.
The two children embraced each other, cheering and leaping for joy.
Volume II: Verification
Time flowed quietly on. In the blink of an eye, several months had passed.
One day, PRL suddenly received a phone call. The caller claimed to be from Columbia University’s National Laboratory. Following PRL’s suggestion, they had used Cobalt-60 in two separate apparatuses to simulate mirror images — turning the Cobalt-60 in one apparatus to the left, and in the other to the right. The result: the two were not symmetric, failing to exhibit the physical characteristics of two objects that are mirror images of each other.
PRL (bursting with joy):
Isn’t this precisely the result predicted in our two children’s paper?
PRL (repeating himself into the phone, over and over, murmuring to himself):
Two physical objects spinning in opposite directions must be mirror images of each other. If they cannot become mirror images of each other, then it is because parity is not conserved.
Old Grandpa PRL’s firm, powerful voice rang out ceaselessly from the receiver, sending ripples through space and time. At Columbia University’s National Laboratory, a group of experimental physicists immediately stopped what they were doing, listened with rapt attention to PRL’s resounding, authoritative, magnetic voice — and tears welled up in their eyes.
They clung to one another in a tight embrace (weeping for joy):
We have finally proven, with facts, that two physical objects can become mirror images of each other by spinning in opposite directions. If they cannot become mirror images of each other, then it is because parity is not conserved. What a remarkable scientific achievement! This moving scientific story shall surely be recorded in the annals of history for all time.
Volume III: Endorsement
A year later, the Nobel Prize Committee for Physics learned of this result and was equally astonished. In collective bewilderment, they sank into their chairs almost simultaneously (hands raised high):
Good heavens! Two physical objects, by spinning in opposite directions, can become mirror images of each other. If they cannot become mirror images of each other, then it is because parity is not conserved. Such a simple truth — and yet it has bewildered human science for centuries!
The experts on the Nobel Prize Committee for Physics (nearly in unison):
This must be richly rewarded!
In October 1957, the Nobel Prize in Physics award ceremony was held as scheduled. The two children, clutching their grand prize, were beside themselves with joy. They immediately went out and bought a huge pile of candy and delicious snacks.
In the process of dividing up the candy and snacks, the two children came that close to coming to blows. To make matters worse, the slightest carelessness left candy wrappers and bread crumbs scattered all over the floor.
Volume IV: Worship
Some years later, Science Bulletin (SB), confronted with the candy wrappers and bread crumbs strewn across the floor (swallowing hard repeatedly):
How classic! This is precisely what scientific research has been lacking. It must be written about at length, proclaimed far and wide, studied diligently, and carried forward — these classics and theories. Otherwise, we Science Bulletin would not deserve to be called SB.
Just then, as it happened, a group of children arrived, brandishing brooms and mops, ready to clean up.
SB was utterly enraged. It charged up to the children, snatched the brooms and mops from their hands, and hurled them to the ground:
You fools (not SB) — how dare you come here to clean up? This is science, do you understand?
The children froze on the spot. They looked left and right (completely baffled):
This litter scattered everywhere is clearly just candy wrappers and bread crumbs!
SB, with a face full of disdain and contempt, cast a cold, sweeping glance over this band of ignorant upstarts, slowly turned around, and cracked its neck from side to side. After a brief pause, without looking back, it strode through the gates of the Chinese Academy of Sciences (tossing back two words):
Childish!
Having passed through the gates, SB seemed to remember something, turned back around, and spat several times in the direction of the children who had come to clean up — spitting with bitter contempt.
—— Translated from https://zhuanlan.zhihu.com/p/701032654.