Altermagnetism, a new third type of magnetism that promises spin-transport applications and reduced heat generation for computer memory, has moved closer to practical implementation. According to Rice University physicist Pengcheng Dai, a research team recently isolated a proposed altermagnet into a single magnetic domain state using uniaxial strain, successfully uncovering the material’s intrinsic magnetic structure.
Overcoming Multidomain Overlaps in Manganese Telluride
Altermagnets like hexagonal manganese telluride typically form multidomain structures. As Dai, the Sam and Helen Worden Professor of Physics and Astronomy at Rice University, points out, magnetic forces in these setups split into separate equivalent domains pointing in different directions to fulfill the hexagonal lattice’s underlying threefold rotational symmetry.
The signals from these coexisting domains frequently overlap during data collection. This overlap makes determining the true underlying magnetic structure difficult because different magnetic arrangements can look nearly identical in raw measurements. Magnetism originates primarily from the magnetic moments of electrons. In larger samples, these moments organize into distinct groups where the magnetic order points in specific directions, varying between neighbors.
Did you know?
Altermagnetism combines the benefits of both ferromagnetism and antiferromagnetism, offering researchers a way to process data at higher frequencies while reducing or eliminating heat in electronic devices.
Applying Uniaxial Strain to Isolate Magnetic States
To solve the overlapping signal problem, Dai’s team applied a uniaxial strain to manganese telluride, stretching the material in a single direction. This mechanical adjustment successfully isolated a single domain state.
Sijie Xu, a Rice graduate student and co-first author of the study published in Physical Review X, noted that the strain application revealed a remarkably sharp feature in the anomalous Hall signal. This signal describes the lateral voltage generated when an electrical current flows through a material due to its magnetic structure.
Tuning the Anomalous Hall Effect via Strain Control
At temperatures of approximately 230 K (minus 45 F), tuning the uniaxial strain can reverse the polarity of the anomalous Hall effect by reversing the flow of its electrons. Zhaoyu Liu, a researcher in Dai’s group and co-first author, stated that because the magnetic interactions remain largely unchanged, this effect likely stems from strain-induced changes in the Berry curvature.
| Control Method | Operational Scope | Observed Impact |
|---|---|---|
| Temperature Adjustment | Requires 150 K shift | Impractical outside the lab. |
| Uniaxial Strain Control | Requires 1% strain change | Achieves equivalent tuning power, altering polarity and Berry curvature. |
While altering temperature can achieve similar tuning results, doing so is impractical outside a laboratory setting. According to the team’s predictions, a 1% change in material strain is equivalent to a 150 K shift in temperature, offering a pathway for device integration.
Implications for Next-Generation Spin-Transport Technologies
The ability to characterize and control altermagnets brings researchers closer to building advanced spin-transport applications. Dai pointed out that future mobile devices could handle memory-intensive tasks at higher frequencies with reduced heat output, extending battery life.
Financial backing for the investigation was provided by the U.S. Department of Energy’s Basic Energy Sciences program, the Robert A. Welch Foundation, the Air Force Office of Scientific Research, the David and Lucile Packard Foundation, the National Science Foundation, the Gordon and Betty Moore Foundation, the Enterprise Science Fund of Intellectual Ventures Management LLC, alongside the state of Florida, the state of Texas through the Texas Center for Superconductivity at the University of Houston, the John J. and Rebecca Moores Endowment, and the Temple Foundation.
Frequently Asked Questions
What is altermagnetism?
Altermagnetism is a third type of magnetism that combines benefits of both ferromagnetism and antiferromagnetism, holding potential for spin-transport memory devices.
How did researchers isolate the manganese telluride domain?
According to Pengcheng Dai’s published findings, the team applied a uniaxial strain to stretch the material in a single direction, successfully creating a single magnetic domain state.
Why is strain control preferred over temperature tuning?
A 1% change in mechanical strain achieves the equivalent tuning capability of a 150 K temperature shift, making strain control more practical for real-world electronic applications.
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