Scientists have successfully demonstrated three-dimensional mapping of altermagnetic spin splitting in the compound chromium antimonide (CrSb), indicating significant advances in our knowledge of this unique material. This discovery, which reveals possible applications for next-generation spintronic devices, is based on cutting-edge spectroscopic techniques.
The term "altermagnetism" refers to collinear magnetism characterized by momentum-dependent band and spin splitting without resulting net magnetization. While this phenomenon has garnered increasing attention, the ability to find materials with significant altermagnetic properties has proven challenging due to the need for precise three-dimensional k-space mapping.
Researchers, led by Yang et al., employed synchrotron-based angle-resolved photoemission spectroscopy (ARPES) to map the altermagnetic properties of CrSb, achieving remarkable resolution and clarity. Their results showed altermagnetic spin splitting values reaching up to ~1.0 eV near the Fermi level, marking the largest altermagnetic band splitting known to date. The width and strength of the splitting indicate potential pathways for future applications, particularly where the unique properties of altermagnets can be utilized.
CrSb is traditionally recognized for its itinerant antiferromagnetism, exhibiting high Néel temperatures (up to 705 K). The research team’s findings imply this material could serve not only as a subject of interest for fundamental physics but also as a platform for exploring emergent phenomena such as unconventional superconductivity, spin currents, and spintronic effects.
One of the key breakthroughs of this study, detailed by the authors, was verifying the bulk-type g-wave altermagnetism through systematic three-dimensional k-space mapping. The authors stated, "Our high-resolution ARPES data from (001)-oriented single crystals unambiguously reveal the characteristic kz and in-plane momentum dependence of the altermagnetic splitting in CrSb." This k-space mapping demonstrates how the unique symmetry of the material allows for distinction between spin-polarized bands.
Addressing the methodology, the researchers utilized model calculations alongside their experimental work to provide comprehensive insights. The tight-binding model analysis indicated the large altermagnetic splitting stems primarily from strong third-nearest-neighbor hopping mediated by Sb ions. The interplay between Cr’s 3d and Sb’s 5p orbitals plays a significant role, as demonstrated by the detailed analysis of the materials’ electronic structure.
This research not only enhances the scientific community’s comprehension of altermagnetic materials but also opens up discussions about the practical applications of CrSb. The authors concluded, "The large band/spin splitting near Fermi level in metallic CrSb, together with its high TN (up to 705 K), paves the way for exploring emergent phenomena and spintronic applications based on altermagnets."
Given the demonstrated properties of CrSb, future studies may focus on manipulating the altermagnetic splitting through external stimuli such as strain or pressure. Identifying materials with even higher altermagnetic properties can lead to advancements across various fields including quantum computing, energy-efficient technologies, and novel superconductors.