Two-electron n-p double quantum dots in carbon nanotubes

Abstract

We consider electron states in n-p double quantum dots defined in a semiconducting carbon nanotube (CNT) by an external potential. We describe formation of extended single-electron orbitals originating from the conduction and valence bands confined in a minimum and a maximum of the external potential, respectively. We solve the problem of a confined electron pair using an exact diagonalization method within the tight-binding approach, which allows for a straightforward treatment of the conduction and valence band states, keeping an exact account for the intervalley scattering mediated by the atomic defects and the electron-electron interaction. The exchange interaction - which in the unipolar double dots is nearly independent of the axial magnetic field (B) and forms singlet-like and triplet-like states - in the n-p system appears only for selected states and narrow intervals of B. In particular the ground-state energy level of a n-p double dot is not split by the exchange interaction and remains four-fold degenerate at zero magnetic field also for a strong tunnel coupling between the dots.

References in corpus (34)

• The electronic properties of graphene
• Coupled quantum dots as quantum gates
• Andreev reflection and Klein tunneling in graphene
• Spin-orbit coupling in curved graphene, fullerenes, nanotubes, and nanotube caps
• Selective transmission of Dirac electrons and ballistic magnetoresistance of \textit{n-p} junctions in graphene
• Coupling of Spin and Orbital Motion of Electrons in Carbon Nanotubes
• Effective low-energy theory for correlated carbon nanotubes
• Measuring electron orbital magnetic moments in carbon nanotubes
• A valley-spin qubit in a carbon nanotube
• Magnetism and correlations in fractionally filled degenerate shells of graphene quantum dots
• Large spin-orbit coupling in carbon nanotubes
• Spin-orbit interaction and anomalous spin relaxation in carbon nanotube quantum dots
• Electrostatic confinement of electrons in graphene nano-ribbons
• Tunable few-electron double quantum dots and Klein tunnelling in ultra-clean carbon nanotubes
• Hubbard-U calculations for Cu from first-principles Wannier functions
• Valley-spin blockade and spin resonance in carbon nanotubes
• Observation and Spectroscopy of a Two-Electron Wigner Molecule in an Ultra-Clean Carbon Nanotube
• Carbon nanotubes in electric and magnetic fields
• Bends In Nanotubes Allow Electric Spin Control and Coupling
• Gate-Defined Quantum Dots on Carbon Nanotubes
• Disorder-mediated electron valley resonance in carbon nanotube quantum dots
• Spin and electronic correlations in gated graphene quantum rings
• Coulomb versus spin-orbit interaction in few-electron carbon-nanotube quantum dots
• Spin-valley blockade in carbon nanotube double quantum dots
• Signatures of spin-orbit interaction in transport properties of finite carbon nanotubes in a parallel magnetic field
• Few-electron physics in a nanotube quantum dot with spin-orbit coupling
• Spin-Orbit Effects in Carbon-Nanotube Double Quantum Dots
• Inter-valley scattering induced by Coulomb interaction and disorder in carbon-nanotube quantum dots
• The low energy spectrum of finite size metallic SWNTs
• The spectrum of interacting metallic carbon nanotubes: Exchange effects and universality
• Tight-binding simulations of electrically driven spin-valley transitions in carbon nanotube quantum dots
• Double Quantum Dots in Carbon Nanotubes
• Electrically driven spin resonance in a bent disordered carbon nanotube
• Dephasing and Hyperfine Interaction in Carbon Nanotubes Double Quantum Dots: The Clean Limit

Cited by in corpus (4)

• Valley two-qubit system in a MoS${}_2$-monolayer gated double quantum dot
• Spin-valley resolved photon-assisted tunneling in carbon nanotube double quantum dots
• Spin-valley dynamics of electrically driven ambipolar carbon-nanotube quantum dots
• Electronic structure of (1e,1h) states of carbon nanotube quantum dots