Kajian Spin-Valleytronic pada Material Monolayer Tungsten Dikalkogenida WX2 (X = S, Se) Berbasis Density Functional Theory

M Khoirul Anwar, Moh. Adhib Ulil Absor, S.Si., M.Sc., Ph.D.

2024 | Skripsi | FISIKA

Telah dilakukan perhitungan komputasional berbasis Density Functional Theory (DFT) pada material monolayer WX₂ (X = S, Se) untuk mengetahui karakteristik elektronik dan valleytronic material. Perhitungan dimulai dengan melakukan optimasi struktur monolayer. Karakteristik elektronik dan valleytronic dapat diketahui dengan menghitung struktur energi, struktur spin, dan berry curvature pada material. Hasil kalkulasi struktur energi menunjukkan bahwa  material WX₂ miliki direct band gap serta terjadi splitting energi di K, K’ dan Q, Q’ point. Hasil kalkulasi spin texture juga menunjukkan bahwa material monolayer  WX₂ hanya memiliki polarisasi spin yang mengarah ke komponen z, selain itu juga menunjukkan bahwa material memiliki pasangan valley conduction band minimum (CBM) dan vallence band maximum (VBM) di K, K’, dan Q, Q’ point. Hasil kalkulasi berry curvature mengkonfirmasi adanya pasanyan valley VBM pada material di K dan K’ point. Dari hasil perhitungan komputasi yang telah dilakukan menunjukkan bahwa WS₂ memiliki potensi untuk dijadikan material spin-valleytronic.

Density Functional Theory (DFT)-based computational calculations have been performed on the monolayer material WX₂ (X = S, Se) to determine the electronic and valleytronic characteristics of the material. The calculation starts with optimizing the monolayer structure. Electronic and valleytronic characteristics can be known by calculating the energy structure, spin structure, and berry curvature of the material. The energy structure calculation shows that WX₂ material has a direct band gap and energy splitting occurs at K, K' and Q, Q' points. The spin texture calculation also shows that the WX₂ monolayer material only has spin polarization that leads to the z component, and also shows that the material has valley conduction band minimum (CBM) and vallence band maximum (VBM) pairs at K, K', and Q, Q' points. The results of berry curvature calculations confirm the presence of VBM valley pair in the material at K and K' points. From the results of the computational calculations that have been carried out, it indicates that WS2 has the potential to be used as a spin-valleytronic material.

Kata Kunci : Density Functional Theory, monolayer WX2 (X = S dan Se), struktur energi, berry curvature, spin-valleytronic.