The search for materials exhibiting unusual electronic properties continues to drive innovation in condensed matter physics, and recent attention has focused on altermagnets, materials with a unique ordering of magnetic moments. Jianhua Du, Xin Peng, and Yuzhi Wang, alongside colleagues, investigate the altermagnet CrSb to determine if it hosts topological states, which could unlock new possibilities in electronics. Their work combines detailed electrical measurements under strong magnetic fields with theoretical calculations, revealing a surprising lack of saturation in the material’s magnetoresistance and evidence of complex charge transport. Crucially, the team confirms a nontrivial topological character in CrSb, indicated by a Berry phase approaching π, establishing a key foundation for exploring and understanding topological states within this emerging class of altermagnetic materials.
CrSb Exhibits Nontrivial Berry Phase Topology
Researchers have discovered a nontrivial Berry phase within chromium antimonide (CrSb), an altermagnet possessing a unique combination of ferromagnetic and antiferromagnetic order. This research explores the topological properties of this material, focusing on a quantum mechanical phenomenon linked to the behaviour of electrons in momentum space. The team performed detailed measurements of the anomalous Hall effect, a phenomenon sensitive to the curvature of electronic band structures, and supported these findings with first-principles calculations to understand the material’s electronic structure and topological characteristics. The results demonstrate a significant anomalous Hall conductivity in CrSb, persisting to relatively high temperatures, which scientists attribute to a nontrivial Berry phase arising from the material’s band structure. Calculations reveal the presence of Dirac-like band crossings near the Fermi level, contributing to a large Berry curvature and, consequently, a substantial anomalous Hall effect. This discovery establishes CrSb as a promising candidate for spintronic applications and materials exhibiting novel topological quantum phenomena, contributing to a growing understanding of altermagnetic materials and their potential for hosting nontrivial topological states, expanding the possibilities for future materials design and device development.
CrSb Exhibits Altermagnetic Weyl Semimetal Behaviour
This research identifies CrSb as an altermagnetic Weyl semimetal, a significant finding because altermagnetism represents a novel form of magnetism where magnetic moments are canted in a way that breaks time-reversal symmetry without breaking spatial inversion symmetry. This unique arrangement leads to distinctive electronic band structures and topological properties. Scientists grew high-quality single crystals of CrSb and performed a range of measurements, including magnetization and electrical transport, to characterize its properties. Crucially, they observed Shubnikov-de Haas oscillations, quantum oscillations in resistivity that reveal details about the material’s Fermi surface, the boundary between occupied and unoccupied electron states.
High-field measurements, conducted using a powerful magnet, further elucidated the Fermi surface. First-principles calculations supported the experimental findings and provided insights into the material’s electronic structure. The team observed the evolution of the Fermi surface with and without spin-orbit coupling, a relativistic effect that significantly alters the electronic band structure and topological properties. These results confirm the existence of topological surface bands in CrSb, protected by the material’s topology and crucial for potential applications. The material’s altermagnetic behaviour is essential for the formation of the Weyl semimetal state, making CrSb a promising new material for exploring fundamental physics related to topological states of matter. The unique spin-polarized surface states could be exploited in spintronic devices, and the material may even contribute to the development of quantum computers and low-power electronics.
CrSb Exhibits Nontrivial Berry Phase Signatures
This study provides compelling evidence for nontrivial topological character within CrSb, establishing a foundation for further investigation of topological states in altermagnets. Researchers performed detailed electrical transport measurements and first-principles calculations, revealing a high and unsaturating magnetoresistance, alongside a multiband charge transport mechanism, under strong magnetic fields. They detected pronounced Shubnikov-de Haas oscillations and Zeeman-effect-induced band splitting, confirming complex electronic behaviour. Analysis of these oscillations, combined with Berry phase calculations and Landau level index fan diagrams, revealed Berry phases approaching π for certain frequency components, strongly suggesting the existence of Weyl-type band structures. The consistency between different analytical methods, including both the Lifshitz-Onsager formula and Landau level index fitting, validates these findings and reinforces the topological nature of the observed electronic states. Further research is needed to fully understand the interplay between altermagnetism and topological behaviour in CrSb and related materials, potentially leading to novel device applications.