Related papers: Ferromagnetism in Quantum Dot Plaquettes
We use density functional theory to investigate the possibility of polar and multiferroic states in free-standing, perovskite-based nanodots at their limit of miniaturization: single unit cell with termination to allow centrosymmetry. We…
Quantum dots connected to larger systems containing a continuum of states like charge reservoirs allow the theoretical study of many-body effects such as the Coulomb blockade and the Kondo effect. Here, we analyze the nonequilibrium Kondo…
Exact eigenstates of the parallel coupled double quantum dots attached to the non-interacting leads taken in zero-bandwidth limit are analytically obtained in each particle and spin sector. The ground state of the half-filled system is…
We investigate interaction-induced valley domain walls in bilayer graphene in the $\nu=0$ quantum Hall state, subject to a perpendicular electric field that is antisymmetric across a line in the sample. Such a state can be realized in a…
In this work,we study the Kondo effect of a quantum dot (QD) connected to leads and to a discrete set of one particle states provided by a quantum box represented by a quantum ring (QR) pierced by a magnetic flux side attached to the QD.…
We present measurements of tunneling magneto-resistance (TMR) in single-wall carbon nanotubes attached to ferromagnetic contacts in the Coulomb blockade regime. Strong variations of the TMR with gate voltage over a range of four conductance…
We present a study of ground state energies and densities of quantum dots in a magnetic field, which takes into account correlation effects through the Current-density functional theory (CDFT). The method is first tested against exact…
We study peculiarities of transport through a Coulomb blockade system tuned to the vicinity of the spin transition in its ground state. Such transitions can be induced in practice by application of a magnetic field. Tunneling of electrons…
Evidence for strong pairing at arbitrary small J/t is provided in a t-J model on the checkerboard lattice for the sign of hopping leading to frustration in hole motion. Destructive quantum interferences suppress Nagaoka ferromagnetism when…
We consider the competition between the Kondo screening effect and ferromagnetic long-range order (FLRO) within a mean-field theory of the Kondo lattice model for low conduction electron densities $n_{c}$. Depending on the parameter values,…
The minimal ferrimagnetism by Lieb's theorem emerges on the T-shaped bipartite lattice composed of four sites, which can be realized experimentally, just as Nagaoka ferromagnetism has been demonstrated experimentally using a quartet…
A quantum dot coupled to ferromagnetically polarized one-dimensional leads is studied numerically using the density matrix renormalization group method. Several real space properties and the local density of states at the dot are computed.…
Within Current Density Functional Theory, we have studied a quantum dot made of 210 electrons confined in a disk geometry. The ground state of this large dot exhibits some features as a function of the magnetic field (B) that can be…
We consider the magnetic field dependence of the chemical potential for parabolically confined quantum dots in a strong magnetic field. Approximate expressions based on the notion that the size of a dot is determined by a competition…
Quantum critical points (QCPs), zero-temperature phase transitions, are windows to fundamental quantum-mechanical phenomena associated with universal behaviour and can provide parallels to the physics of black holes. Magnetic QCPs have been…
Using the Density Matrix Renormalization Group and two-leg ladders, we investigate an electronic two-orbital Hubbard model including plaquette diagonal hopping amplitudes. Our goal is to search for regimes where charges added to the undoped…
A comprehensive theory for electronic transport in itinerant ferromagnets is developed. We first show that the Q-field theory used previously to describe a disordered Fermi liquid also has a saddle-point solution that describes a…
We present a theory of electronic properties of gated triangular graphene quantum dots with zigzag edges as a function of size and carrier density. We focus on electronic correlations, spin and geometrical effects using a combination of…
We investigate the ground-state properties of triangular graphene nanoflakes with zigzag edge configurations. The description of zero-dimensional nanostructures requires accurate many-body techniques since the widely used density-functional…
Electronic states and transport phenomena in semiconductor quantum dots are studied theoretically. Taking account of the electron-electron Coulomb interaction by the exact diagonalization method, the ground state and low-lying excited…