Quantum magnetotransport properties of aMoS2monolayer

Abstract

We study transport properties of a MoS 2 monolayer in the presence of a perpendicular magnetic field B. We derive and discuss its band structure and take into account spin and valley Zeeman effects. Compared to a conventional two-dimensional electron gas, these effects lead to new quantum Hall plateaus and new peaks in the longitudinal resistivity as functions of the magnetic field. The field B leads to a significant enhancement of the spin splitting in the conduction band, to a beating of the Shubnikov-de Haas (SdH) oscillations in the low-field regime, and to their splitting in the high-field regime. The Zeeman fields suppress significantly the beating of the SdH oscillations in the low-field regime and strongly enhance their splitting at high fields. The spin and valley polarizations show a similar beating pattern at low fields and are clearly separated at high fields in which they attain a value higher than 90%.

Topologically induced fractional Hall steps in the integer quantum Hall regime ofMoS2

“…It should be noted that two energy scales arise in the solution of Hamiltonian(4). This is in contrast to the case where the topological parameters are absent 23 …”

“…Now, we shall point out few distinct features of the above Landau levels (Eq.10) which are in contrast to the case of without topological terms but in presence of spin and valley dependent Zeeman term as considered in Ref. [23]. The spin splitting Landau levels (E n,↑,τ,p − E n,↓,τ,p ) are valley dependent and tunable by varying magnetic field and controlling topological parameters via gate voltage.…”

“…(10), see the second term under the square root the topological factor β is multiplied with n which is in complete contrast to the valley dependent Zeeman effect as treated in Ref. [23]. At strong magnetic field, the effect of the topological parameter is expected to be dominant over Dirac kinetic energy terms.…”

“…On the other hand in Ref. [23], though a spin dependent Zeeman term causes valley dependent spin splitting Landau levels, but the scope of tuning the spin splitting is limited to magnetic field only. The topological parameters are intrinsically associated with Landau level index 'n' which suggests that spin splitting will depend on 'n' strongly.…”

“…We have checked that topologically induced energy correction is 3.2 meV at B = 0.5 T for a typical Landau level n = 25, on the other hand Zeeman energy is 0.057 meV which is too small and can be ignored as compared to the spin-orbit as well as the terms containing topological parameters α and β. Zeeman terms, baring Ref. [23] which of course considers magnetically doped MoS 2 , are usually ignored. See for example Refs.…”