Large Band Splitting in g-Wave Altermagnet CrSb

Altermagnetism (AM), a newly discovered magnetic state, ingeniously integrates the properties of ferromagnetism and antiferromagnetism, representing a significant breakthrough in the field of magnetic materials. Despite experimental verification of some typical AM materials, such as MnTe and MnTe_{2}, the pursuit of AM materials that feature larger spin splitting and higher transition temperature is still essential. Here, our research focuses on CrSb, which possesses Néel temperature of up to 700 K and giant spin splitting near the Fermi level (E_{F}). Utilizing high-resolution angle-resolved photoemission spectroscopy and density functional theory calculations, we meticulously map the three-dimensional electronic structure of CrSb. Our photoemission spectroscopic results on both (0001) and (101[over ¯]0) cleavages of CrSb collaboratively reveal unprecedented details on AM-induced band splitting, and subsequently pin down its unique bulk g-wave symmetry through quantitative analysis of the angular and photon-energy dependence of spin splitting. Moreover, the observed spin splitting reaches the magnitude of 0.93 eV near E_{F}, the most substantial among all confirmed AM materials. This Letter not only validates the nature of CrSb as a prototype g-wave-like AM material but also underscores its pivotal role in pioneering applications in spintronics.