We report the doping effects of cobalt on van der Waals (vdW) magnet Fe5GeTe2. A series of (Fe1−xCox)5GeTe2 (0≤x≤0.44) single crystals have been successfully grown, their structural, magnetic and transport properties are investigated. For x=0.20, The Curie temperature TC increases from 276~K to 337~K. Moreover, the magnetic easy-axis is reoriented to the ab-plane from the c-axis in undoped Fe5GeTe2 with largely enhanced magnetic anisotropy. These magnetic properties would make (Fe0.8Co0.2)5GeTe2 more effective in stabilizing magnetic order in the two-dimensional limit. A complex magnetic phase diagram is identified on the higher doping side. The x=0.44 crystal first orders ferromagnetically at TC=363~K then undergoes an antiferromagnetic transition at TN=335~K. Furthermore magnetic-field-induced spin-flop transitions are observed for the AFM ground state. Our work reveals (Fe1−xCox)5GeTe2 as promising candidates for developing new spin-related applications and proposes a method to engineer the magnetic properties of vdW magnet.
@article{arxiv.2003.02728,
title = {Tunable magnetic properties in van der Waals crystals (Fe$_{1-x}$Co$_x$)$_5$GeTe$_2$},
author = {Congkuan Tian and Feihao Pan and Sheng Xu and Kun Ai and Tian-long Xia and Peng Cheng},
journal= {arXiv preprint arXiv:2003.02728},
year = {2020}
}