Strain-mediated ferromagnetism and low-field magnetic reversal in Co doped monolayer $$WS_2$$

Abstract

AbstractStrain-mediated magnetism in 2D materials and dilute magnetic semiconductors hold multi-functional applications for future nano-electronics. Herein, First principles calculations are employed to study the influence of biaxial strain on the magnetic properties of Co-doped monolayer $$WS_2$$ W S 2 . The non-magnetic $$WS_2$$ W S 2 shows ferromagnetic signature upon Co doping due to spin polarization, which is further improved at low compressive (-2 %) and tensile (+2 %) strains. From the PDOS and spin density analysis, the opposite magnetic ordering is found to be favourable under the application of compressive and tensile strains. The double exchange interaction and p-d hybridization mechanisms make Co-doped $$WS_2$$ W S 2 a potential host for magnetism. More importantly, the competition between exchange and crystal field splittings, i.e. ($$\Delta _{ex}>\Delta _{cfs}$$ Δ ex > Δ cfs ), of the Co-atom play pivotal roles in deciding the values of the magnetic moments under applied strain. Micromagnetic simulation reveals, the ferromagnetic behavior calculated from DFT exhibits low-field magnetic reversal (190 Oe). Moreover, the spins of Co-doped $$WS_2$$ W S 2 are slightly tilted from the easy axis orientations showing slanted ferromagnetic hysteresis loop. The ferromagnetic nature of Co-doped $$WS_2$$ W S 2 suppresses beyond $$\pm 2~\%$$ ± 2 % strain, which is reflected in terms of decrease in the coercivity in the micromagnetic simulation. The understanding of low-field magnetic reversal and spin orientations in Co-doped $$WS_2$$ W S 2 may pave the way for next-generation spintronics and straintronics applications.