Inherited itinerant ferromagnetism on the polar surface in Na-intercalated antiferromagnet NaCrTe₂

Manipulating magnetism in two-dimensional (2D) van der Waals (vdW) materials arouses considerable and ongoing interest in fundamental physics and potential applications in next-generation spintronics. Here, we have investigated the underlying electronic structures of bulk vdW magnets CrTe₂and NaCrTe₂, by carrying out high-resolution angle-resolved photoemission spectroscopy studies and first-principles calculations. In CrTe₂, strong out-of-plane band dispersions and metallic Fermi surface are observed, accompanied by temperature-dependent ferromagnetic (FM) energy gain behavior which directly confirms its itinerant origin. In sharp contrast, NaCrTe₂turns into an<i>A</i>-type antiferromagnetic (AFM) semiconductor in calculations and transport measurements. Remarkably, robust ferromagnetism inherited from CrTe₂is distinguished on the polar surface of AFM NaCrTe₂. Our results not only reveal the itinerant FM mechanism of CrTe₂, but also demonstrate that chemical doping is a powerful tuning knob to manipulate the properties of 2D magnetic material. Moreover, we establish NaCrTe₂as an excellent AFM semiconductor platform with robust surface ferromagnetism, which is promising in practical applications.