Determining Interaction Enhanced Valley Susceptibility in Spin-Valley-Locked MoS₂

Abstract

Two-dimensional transition metal dichalcogenides (TMDCs) are recently emerged electronic systems with various novel properties, such as spin-valley locking, circular dichroism, valley Hall effect, and superconductivity. The reduced dimensionality and large effective masses further produce unconventional many-body interaction effects. Here we reveal strong interaction effects in the conduction band of MoS 2 by transport experiment. We study the massive Dirac electron Landau levels (LL) in high-quality MoS 2 samples with field-effect mobilities of 24 000 cm 2 /(V•s) at 1.2 K. We identify the valley-resolved LLs and low-lying polarized LLs using the Lifshitz−Kosevitch formula. By further tracing the LL crossings in the Landau fan diagram, we unambiguously determine the density-dependent valley susceptibility and the interaction enhanced g-factor from 12.7 to 23.6. Near integer ratios of Zeeman-to-cyclotron energies, we discover LL anticrossings due to the formation of quantum Hall Ising ferromagnets, the valley polarizations of which appear to be reversible by tuning the density or an in-plane magnetic field. Our results provide evidence for many-body interaction effects in the conduction band of MoS 2 and establish a fertile ground for exploring strongly correlated phenomena of massive Dirac electrons.

Enhancing and controlling valley magnetic response in MoS2/WS2 heterostructures by all-optical route

“…2 for more details), while the g factor of WS 2 oscillates around 4 which corresponds to the value of undoped samples in previous studies 56 . Note that the g factor evolution of MoS 2 with electron-doping in our work is in good harmony with the recent transport measurements 61 . For the continuous and monotonical decline in g factor of MoS 2 , it can be understood as the electron-doping tuned by optical pumping.…”

Tunable spin-valley coupling in layered polar Dirac metals

“…The prismatic layer is regarded as a graphene-like material with different A-and Bsite atoms that break the inversion symmetry. Therefore, the electron and hole valleys located at the K and K′ points are well described by massive Dirac fermions exhibiting valley-contrasting spin polarization perpendicular to the 2D plane [10][11][12][13] . Such spinvalley coupling has indeed been demonstrated through its distinctive optical and transport properties, such as valley-dependent circular dichroic photoluminescence [14][15][16] and nonreciprocal charge transport 17 .…”

Electronic Transport in Few-Layer Black Phosphorus

“…where ω is the cyclotron frequency, λ T ðÞ stands for the thermal factor, ϕ ↑, ↓ is the corrected Berry phase taking Zeeman splitting into consideration, and τ ↑, ↓ is the spin-resolved quantum scattering times. The extracted spin-dependent quantum scattering time at different temperatures and gate voltages are presented in [48]. The mechanism behind this spin-selective scattering process remains to be further addressed.…”