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

Abstract

Two-dimensional semiconductors, including transition metal dichalcogenides, are of interest in electronics and photonics but remain nonmagnetic in their intrinsic form. Previous efforts to form two-dimensional dilute magnetic semiconductors utilized extrinsic doping techniques or bulk crystal growth, detrimentally affecting uniformity, scalability, or Curie temperature. Here, we demonstrate an in situ substitutional doping of Fe atoms into MoS 2 monolayers in the chemical vapor deposition growth. The iron atoms substitute molybdenum sites in MoS 2 crystals, as confirmed by transmission electron microscopy and Raman signatures. We uncover an Fe-related spectral transition of Fe:MoS 2 monolayers that appears at 2.28 eV above the pristine bandgap and displays pronounced ferromagnetic hysteresis. The microscopic origin is further corroborated by density functional theory calculations of dipoleallowed transitions in Fe:MoS 2. Using spatially integrating magnetization measurements and spatially resolving nitrogen-vacancy center magnetometry, we show that Fe:MoS 2 monolayers remain magnetized even at ambient conditions, manifesting ferromagnetism at room temperature.

Enhanced Electrical Performance of Monolayer MoS2 with Rare Earth Element Sm Doping

“…It can be seen from Figure 2 b that undoped MoS 2 had a strong PL peak at about 1.82 eV, implying the MoS 2 is a direct band gap semiconductor. However, the PL intensities of Sm-doped MoS 2 were observed to be much lower with a 30 meV blue shift than that of undoped MoS 2 , which was consistent with previous predictions of the optical quenching of the PL intensities due to distortion of the MoS 2 lattice [ 10 ]. This may be ascribed to the introduction of new defects due to lattice distortion by the doped Sm ions, as well as changes in band gap width.…”

“…Due to the competing effects of lattice strain and Sm 3+ charge doping on the Raman shift, the overall blue shift of the and peak was relatively small [ 31 ]. Furthermore, the distortion of the MoS 2 lattice could give rise to the optical quenching of the PL intensities [ 10 ]. It can be seen from Figure 2 b that undoped MoS 2 had a strong PL peak at about 1.82 eV, implying the MoS 2 is a direct band gap semiconductor.…”

“…However, in these previous doping schemes, ion injection and surface charge transfer in monolayer 2D-TMDC doping were often not stable enough, thus limiting their application [ 6 , 7 ]. Substitution the doping of 2D-TMDCs has been widely explored for materials applications in electronic and optoelectronic [ 7 ], as well as room-temperature ferromagnetism, applications [ 8 , 9 , 10 ]. Transition elements have been used as cationic substitutes for doped 2D-TMDCs, e.g., the Nb ion-doped 2D-TMDCs achieving p-type [ 7 ] transport characteristics and the Re ion-doped 2D-TMDCs achieving nearly degenerate n-type doping [ 11 ].…”

“…Transition elements have been used as cationic substitutes for doped 2D-TMDCs, e.g., the Nb ion-doped 2D-TMDCs achieving p-type [ 7 ] transport characteristics and the Re ion-doped 2D-TMDCs achieving nearly degenerate n-type doping [ 11 ]. Moreover, in recent studies, Fu’s group confirmed ferromagnetism in monolayer MoS 2 via in situ Fe-doping at room temperature [ 10 ] and Pham’s group enhanced tunable ferromagnetism in V-doped WSe 2 monolayers at 0.5–5 at% V concentrations [ 9 ]. Additionally, other transition metal elements in the in situ substitution of MoS 2 -doped for electronic application studies have been demonstrated, such as for Mn [ 12 ].…”

2D Polarized Materials: Ferromagnetic, Ferrovalley, Ferroelectric Materials, and Related Heterostructures

“…PL spectroscopy showed the emission of Fe is around 2.28 eV, and the presence of Fe atom was also proved by STEM and Raman spectroscopy. With the measurement of nitrogen‐vacancy center magnetometry, a large local field of 0.5 ± 0.1 mT was observed, and hysteresis loop measured by superconducting quantum interference devices revealed T C has not been reached at 300 K. [ 87 ]…”