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)5GeTe2 (x = 0–0.47) single crystals and a comprehensive investigation of cobalt (Co) doping effects on the magnetic and transport properties. The Curie temperature (TC) 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 (TN) 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.