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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The coexistence of electric and magnetic orders with intrinsic coupling, referred to as magnetoelectric coupling in multiferroics, has been extensively studied in oxide materials but remains relatively unexplored in van der Waals materials. Among these, CuCrP 2 S 6 (CCPS) is notable for its emergent antiferromagnetic (AFM) and antiferroelectric (AFE) characteristics. However, investigations into magnetoelectric coupling in CCPS are limited, and the effects of dopants on its magnetic properties have yet to be fully addressed. In this study, we synthesized CuCr 1- x Fe x P 2 S 6 (CCFPS) samples using the chemical vapor transport (CVT) method to investigate the influence of iron doping on the magnetic and nonlinear optical properties of the CCFPS system. Our results indicate that the AFM state is preserved, while the Néel temperature ( T N ) varies with the doping concentration. First-principles calculations were employed to assess the exchange interactions among magnetic atoms. Notably, for samples with doping concentrations x < 0.5, we observed both magnetic-dielectric coupling and second harmonic generation (SHG) effects. However, these effects were absent at higher doping levels. Furthermore, our analysis revealed a distinct odd-even dependence of SHG, suggesting the presence of interlayer symmetry-breaking coupling. These findings advance our understanding of two-dimensional (2D) multiferroic materials and lay the groundwork for designing and optimizing magnetoelectric coupling materials with enhanced performance.