Nonlinearities in Altermagnetic Materials

Nonlinear responses in magnetic materials present significant potential across diverse applications, including spin-wave electronics, magnetic devices, and medical imaging. It is essential to recognize that these responses can differ between ferromagnets and antiferromagnets due to variations in material symmetries. Altermagnetic materials, a newly identified class of magnets, exhibit characteristics that merge elements of both ferromagnets and antiferromagnets. With the help of first-principles calculation, we investigate the second-order nonlinear response in various types of altermagnets, specifically p-wave, d-wave, g-wave, and i-wave altermagnets, with particular attention to their symmetrical properties in this study. Furthermore, given the pronounced role of quantum geometry in nonlinear currents, we analyze the role of topological characteristics on the second-order nonlinear response in selected altermagnets. ​The findings presented in this work establish a foundation for the potential application of nonlinear responses in altermagnetic materials.