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

Anjan Kumar Jena,Mousam Charan Sahu,Sanjeev K Gupta,J Mohanty,Sandhyarani Sahoo,Ajit Kumar Sahoo,Satyaprakash Sahoo,Neha Kapila Sharma,Rajeev Ahuja,Sameer Kumar Mallik

doi:10.1038/s41598-022-06346-w

Abstract

Strain-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. The non-magnetic WS_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 a potential host for magnetism. More importantly, the competition between exchange and crystal field splittings, i.e. (Delta _{ex}>Delta _{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 are slightly tilted from the easy axis orientations showing slanted ferromagnetic hysteresis loop. The ferromagnetic nature of Co-doped WS_2 suppresses beyond pm 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 may pave the way for next-generation spintronics and straintronics applications.

Highlights

Strain-mediated magnetism in 2D materials and dilute magnetic semiconductors hold multifunctional applications for future nano-electronics
Among various 2D materials, transition metal di-chalcogenides (TMDCs) such as MX2 (M: Mo, W, etc.; X: S, Se, etc.) marks significant attention owing to their unique potential applications in field-effect transistor (FET), photodetectors, catalysis, Li-ion batteries etc[1,2,4,5]
We explore the strain-induced ferromagnetism in transition metal Co-doped WS2 monolayer by using firstprinciples DFT calculations and micromagnetic simulation

Summary

Introduction

Strain-mediated magnetism in 2D materials and dilute magnetic semiconductors hold multifunctional applications for future nano-electronics. Luo et al obtained FM behavior in Al-doped WS2 under applied compressive strain, while unable to produce any magnetic moment under tensile strain[30]. We employed DFT calculations to understand the mechanism of FM behavior in Co-doped WS2 ML at biaxial compressive and tensile strain.

Results

Conclusion