Abstract

Lateral charge transport of a two-dimensional (2D) electronic system can be much influenced by feeding a current into another closely spaced 2D conductor, known as the Coulomb drag phenomenon – a powerful probe of electron-electron interactions and collective excitations. Yet the materials compatible for such investigations remain limited to date. Especially, gapped 2D semiconductors with inherently large correlations over a broad gate range have been rarely accessible at low temperatures. Here, we show the emergence of a large drag response (drag resistance Rdrag at the order of kΩ, with a passive-to-active drag ratio up to ∼0.6) in a semiconductor-semimetal hybrid, realized in a graphene-MoS₂ heterostructure isolated by an ultrathin 3 nm hexagonal boron nitride (h-BN) dielectric. We observe a crossover of T- to T₂-dependence of Rdrag, separated by a characteristic temperature Td ∼EF/kFd (d being the interlayer distance), in echo with the presence of a metal-insulator transition in the semiconducting MoS2. Interestingly, the current nanostructure allows the decoupling of intralayer interaction-driven drag response by varying density in one layer with that in the other layer kept constant. A large Wigner–Seitz radius rs (> 10 within the density range of 1 to 4×1012cm⁻²) in the massive Schrödinger carriers in MoS₂ is thus identified to dominate the quadratic dependence of total carriers in the drag system, while the massless Dirac carriers in graphene induce negligible drag responses as a function of carrier density. Our findings establish semiconductor-semimetal hybrid as a platform for studying unique interaction physics in Coulomb drag systems.

Abstract

Lateral charge transport of a two-dimensional (2D) electronic system can be much influenced by feeding a current into another closely spaced 2D conductor, known as the Coulomb drag phenomenon – a powerful probe of electron-electron interactions and collective excitations. Yet the materials compatible for such investigations remain limited to date. Especially, gapped 2D semiconductors with inherently large correlations over a broad gate range have been rarely accessible at low temperatures. Here, we show the emergence of a large drag response (drag resistance Rdrag at the order of kΩ, with a passive-to-active drag ratio up to ∼0.6) in a semiconductor-semimetal hybrid, realized in a graphene-MoS₂ heterostructure isolated by an ultrathin 3 nm hexagonal boron nitride (h-BN) dielectric. We observe a crossover of T- to T₂-dependence of Rdrag, separated by a characteristic temperature Td ∼EF/kFd (d being the interlayer distance), in echo with the presence of a metal-insulator transition in the semiconducting MoS2. Interestingly, the current nanostructure allows the decoupling of intralayer interaction-driven drag response by varying density in one layer with that in the other layer kept constant. A large Wigner–Seitz radius rs (> 10 within the density range of 1 to 4×1012cm⁻²) in the massive Schrödinger carriers in MoS₂ is thus identified to dominate the quadratic dependence of total carriers in the drag system, while the massless Dirac carriers in graphene induce negligible drag responses as a function of carrier density. Our findings establish semiconductor-semimetal hybrid as a platform for studying unique interaction physics in Coulomb drag systems.

Abstract

Lateral charge transport of a two-dimensional (2D) electronic system can be much influenced by feeding a current into another closely spaced 2D conductor, known as the Coulomb drag phenomenon – a powerful probe of electron-electron interactions and collective excitations. Yet the materials compatible for such investigations remain limited to date. Especially, gapped 2D semiconductors with inherently large correlations over a broad gate range have been rarely accessible at low temperatures. Here, we show the emergence of a large drag response (drag resistance Rdrag at the order of kΩ, with a passive-to-active drag ratio up to ∼0.6) in a semiconductor-semimetal hybrid, realized in a graphene-MoS₂ heterostructure isolated by an ultrathin 3 nm hexagonal boron nitride (h-BN) dielectric. We observe a crossover of T- to T₂-dependence of Rdrag, separated by a characteristic temperature Td ∼EF/kFd (d being the interlayer distance), in echo with the presence of a metal-insulator transition in the semiconducting MoS2. Interestingly, the current nanostructure allows the decoupling of intralayer interaction-driven drag response by varying density in one layer with that in the other layer kept constant. A large Wigner–Seitz radius rs (> 10 within the density range of 1 to 4×1012cm⁻²) in the massive Schrödinger carriers in MoS₂ is thus identified to dominate the quadratic dependence of total carriers in the drag system, while the massless Dirac carriers in graphene induce negligible drag responses as a function of carrier density. Our findings establish semiconductor-semimetal hybrid as a platform for studying unique interaction physics in Coulomb drag systems.

Abstract

Lateral charge transport of a two-dimensional (2D) electronic system can be much influenced by feeding a current into another closely spaced 2D conductor, known as the Coulomb drag phenomenon – a powerful probe of electron-electron interactions and collective excitations. Yet the materials compatible for such investigations remain limited to date. Especially, gapped 2D semiconductors with inherently large correlations over a broad gate range have been rarely accessible at low temperatures. Here, we show the emergence of a large drag response (drag resistance Rdrag at the order of kΩ, with a passive-to-active drag ratio up to ∼0.6) in a semiconductor-semimetal hybrid, realized in a graphene-MoS₂ heterostructure isolated by an ultrathin 3 nm hexagonal boron nitride (h-BN) dielectric. We observe a crossover of T- to T₂-dependence of Rdrag, separated by a characteristic temperature Td ∼EF/kFd (d being the interlayer distance), in echo with the presence of a metal-insulator transition in the semiconducting MoS2. Interestingly, the current nanostructure allows the decoupling of intralayer interaction-driven drag response by varying density in one layer with that in the other layer kept constant. A large Wigner–Seitz radius rs (> 10 within the density range of 1 to 4×1012cm⁻²) in the massive Schrödinger carriers in MoS₂ is thus identified to dominate the quadratic dependence of total carriers in the drag system, while the massless Dirac carriers in graphene induce negligible drag responses as a function of carrier density. Our findings establish semiconductor-semimetal hybrid as a platform for studying unique interaction physics in Coulomb drag systems.