Uniaxial strain reveals new way to tune electron flow in altermagnet material

Researchers at Rice University have demonstrated a novel method to manipulate electron flow in an altermagnetic material by applying uniaxial strain, according to a study published in Physical Review X. The breakthrough involves hexagonal manganese telluride, an altermagnet with potential applications in spin-transport technologies. By inducing a single magnetic domain state through controlled strain, the team was able to observe and measure previously obscured magnetic properties, offering new insights into how altermagnets behave under external stress. The discovery centers around the behavior of magnetic domains within manganese telluride. Altermagnets, unlike traditional ferromagnets or antiferromagnets, exhibit unique magnetic properties that could enable more efficient data storage and processing. However, these materials often form complex, multidomain structures where magnetic moments align in multiple directions, complicating analysis. The Rice team addressed this challenge by subjecting the material to uniaxial strain, a process that stretches the crystal along a single axis. This technique effectively reduced the material to a single magnetic domain, simplifying the measurement of its intrinsic magnetic structure. According to the researchers, the application of uniaxial strain not only clarified the magnetic configuration but also revealed a distinct anomaly in the material’s response to electric currents. Specifically, they observed a sharp feature in the anomalous Hall signal, which measures the lateral voltage produced when an electric current passes through a magnetic material. At temperatures below approximately 230 K (-45°F), the strain could reverse the polarity of this effect by altering the direction of electron flow. This phenomenon, described as non-typical for conventional magnets, suggests a deeper connection between mechanical deformation and electronic transport in altermagnets. The findings highlight the role of strain in modifying the Berry curvature, an abstract concept in quantum mechanics that influences how electrons move in magnetic fields. The team found that even though the fundamental magnetic interactions remained stable, the applied strain induced measurable changes in the Berry curvature, thereby affecting the anomalous Hall effect. This insight opens up possibilities for tuning the material’s electronic properties without relying solely on temperature adjustments, which are impractical for real-world applications. One of the key advantages of this approach lies in its scalability. The researchers noted that a 1% change in strain corresponds to a 150 K shift in temperature, meaning that minor mechanical deformations could achieve effects similar to extreme thermal conditions. This has implications for developing more energy-efficient devices, particularly in computing and memory technologies. For instance, future electronics could operate with greater speed and efficiency while generating significantly less heat, potentially extending battery life in portable devices. The study, led by Pengcheng Dai, the Sam and Helen Worden Professor of Physics and Astronomy, and involving graduate student Sijie Xu and researcher Zhaoyu Liu, marks a critical step toward understanding and utilizing altermagnetism. Their work provides a framework for further exploration into how mechanical strain can be used to control magnetic and electronic behaviors in advanced materials. As the field continues to evolve, such discoveries may pave the way for innovations in next-generation technologies that rely on precise manipulation of spin and charge transport.