Enhanced magnetic and electrical properties of Co-doped Fe₅GeTe₂

The layered van der Waals material Fe5GeTe2 (F5GT) has emerged as a captivating candidate for room-temperature spintronics, boasting inherent ferromagnetic behavior. Nevertheless, the intricate magnetic characteristics of F5GT beckon a deeper exploration. Here, we present the synthesis of (Fe1-xCox)(5)GeTe2 (x = 0-0.47) single crystals and a comprehensive investigation of cobalt (Co) doping effects on the magnetic and transport properties. The Curie temperature (T-C) enhancement of F5GT is revealed in magnetic measurements, surpassing room temperature and reaching 325 K at x = 0.24. Furthermore, Co doping induces an adjustment of the easy magnetization direction of F5GT toward the in-plane orientation, affording a significant amplification of magnetic anisotropy. Notably, for x = 0.47, an antiferromagnetic ground state emerges with a transition temperature (T-N) of 340 K, accompanied by field-induced spin-flop transitions. In addition, our electrical transport measurements yield complementary insights into the influence of Co doping on F5GT, unraveling the understanding of the strong spin-charge coupling within the materials. First-principles calculations demonstrate that Co doping plays an important role in the influence of interlayer stacking and magnetic ground state. This investigation unlocks the enormous potential of Co-doped F5GT for high-performance room-temperature spintronics applications.