High Coercivity and Magnetization in WSe₂ by Codoping Co and Nb

Abstract

Introducing ferromagnetism in transition metal dichalcogenides has attracted lots of attention due to the possible applications in spintronics devices. Generally, single magnetic element doping is used to introduce magnetism. However, mostly, weak ferromagnetism is observed. In this work, codoping of two kinds of transition metals (Nb and Co) into WSe2 is used to study its magnetic properties. In detail, single crystal WSe2 is codoped with 4 at% Co and various concentrations of Nb by employing the physical ion implantation method. Raman, X‐ray diffraction and X‐ray photoelectron spectroscopy results reveal the effective substitutional doping of implanted elements (Co and Nb). Magnetic measurements illustrate that both un‐doped and 4 at% Co doped WSe2 show weak ferromagnetism whereas magnetization is strongly enhanced when Co and Nb are codoped into WSe2. The magnetization is comparable with a ferromagnet, which may be attributed to Co, Nb doping and defects. In addition, a large coercivity of ≈1.2 kOe is observed in the 1 at% Nb–4 at% Co codoped WSe2 sample, which may be ascribed to the combined effect of doping‐induced stress, defect‐dictated pinning and anisotropy of NbSe bond owing to the charge transfer between Nb and Se ions.

Tunable and Robust Near-Room-Temperature Intrinsic Ferromagnetism of a van der Waals Layered Cr-Doped 2H-MoTe2 Semiconductor with an Out-of-Plane Anisotropy

“…In addition, for the Cr-2.1 NSs, a maximum H c up to 6322 Oe for out-of-plane orientation (7074 Oe for in-plane orientation) is observed at 20 K, unlike the monotonic increase of the thermomagnetic curves with decreasing temperature (Figures 3f and S16b, Tables S4 and S5, Supporting Information), which is the highest value reported so far in TMDC-based diluted magnetic semiconductors. 55,56 After ultrasonic thinning treatment, only a T c at ≈220 K could be identified from the thermomagnetic curves (M−T, zero-field cooling (ZFC) and field cooling (FC) modes) and spontaneous magnetization curve of the Cr-2.1 NSs (Figure S15c,d, Supporting Information). Compared with its Cr-2.1 bulk counterpart, the high near-room-temperature ferromagnetic transition point disappears for the Cr-2.1 NSs due to the thermal fluctuations, 54 which is always significant in two-dimensional crystals with atomically thin thickness.…”

Enabling room temperature ferromagnetism in monolayer MoS2 via in situ iron-doping

“…Another technique is based on ion implantation and the idea of co-doping, giving rise to very high saturation magnetization values of 60.62 emu g −1 , but ferromagnetism is limited to a T C around 10 K (ref. 22 ). These previous findings warrant a continued search for TMD-based DMSs that feature RT ferromagnetism and a scalable in situ growth technique that does not rely on detrimental postprocessing techniques.…”

Exciton Dynamics in Mn/Ni Dual‐doped Semiconductor Quantum Dots

“…This suggests that (Mn, Ni) codoping has enhanced the magnetic response which might be due to the mutual interactions between the Mn and the Ni as well as with that of the host that takes part in magnetic exchange interaction, as observed in earlier codoped system reported in thin film or bulk. [26,36] It is worth mentioning here, although there is a significant percentage of Mn doped inside the samples, we do not observe antiferromagnetic coupling in these QDs. This is due to the small particle size, wherein the host QDs has a very small number of atoms per QDs and the dopants are uniformly distributed inside the QDs.…”