Related papers: Spin-Excitation-Instability-Induced Quantum Phase …
The two-layer square lattice quantum antiferromagnet with spins 1/2 shows a zero-field magnetic order-disorder transition at a critical ratio of the inter-plane to intra-plane couplings. Adding a uniform magnetic field tunes the system to…
Spin relaxation in quantum Hall ferromagnet regimes is studied. As the initial non-equilibrium state, a coherent deviation of the spin system from the ${\vec B}$ direction is considered and the breakdown of this Goldstone-mode state due to…
We explore non-analytic quantum phase dynamics of dipolar exciton condensates formed in a system of 1D quantum layers subjected to voltage quenches. We map the exciton condensate physics on to the pseudospin ferromagnet model showing an…
It is shown that topological insulating phases driven by interactions can be realized without the need for spin-orbit coupling or large intersite interaction in a two-dimensional system of spin-1/2 fermions with a single pair of…
We study the thermodynamic phases of a gas of spin-1/2 atoms in the Hartree-Fock approximation. Our main result is that, for repulsive or weakly-attractive inter-component interaction strength, the superfluid and ferromagnetic phase…
We present a theoretical realization of quantum spin and quantum valley Hall effects in silicene. We show that combination of an electric field and intrinsic spin-orbit interaction leads to quantum phase transitions at the charge neutrality…
We derive the random-phase approximation for spin excitations in general multi-band Hubbard models, starting from a collinear ferromagnetic Hartree-Fock ground state. The results are compared with those of a recently introduced variational…
Cyclotron spin-flip excitation in a nu=2 quantum Hall system, being separated from the ground state by a slightly smaller gap than the cyclotron energy and from upper magnetoplasma excitation by the Coulomb gap [S. Dickmann and I.V.…
We present a comprehensive analysis of the magnetic excitations and electronic properties of fully quantum double-exchange ferromagnets, i.e., systems where ferromagnetic ordering emerges from the competition between spin, charge, and…
A bilayer system of two-dimensional electron gases in a perpendicular magnetic field exhibits rich phenomena. At total filling factor $\nu_{tot} = 1$, as one increases the layer separation, the bilayer system goes from an interlayer…
Condensates of spin-1 sodium display rich spin dynamics due to the antiferromagnetic nature of the interactions in this system. We use Faraday rotation spectroscopy to make a continuous and minimally destructive measurement of the dynamics…
Spin waves are collective excitations of magnetic systems. An attractive setting for studying long-lived spin-wave physics is the quantum Hall (QH) ferromagnet, which forms spontaneously in clean two-dimensional electron systems at low…
We investigate theoretically the effects of intralayer and interlayer exchange in biased double-layer electron and hole systems, in the absence of a magnetic field. We use a variational Hartree-Fock-like approximation to analyze the effects…
In higher Landau levels (N>0) and around filling factors nu =4N+1, a two-dimensional electron gas in a double-quantum-well system supports a stripe groundstate in which the electron density in each well is spatially modulated. When a…
The tilting angular dependence of the energy gap was measured in the bilayer quantum Hall state at the Landau level filling $\nu=1$ by changing the density imbalance between the two layers. The observed gap behavior shows a continuous…
In condensed matter physics, the study of electronic states with SU(N) symmetry has attracted considerable and growing attention in recent years, as systems with such a symmetry can often have a spontaneous symmetry-breaking effect giving…
We study the effects of marginally spinful electron-electron interactions on the low-energy instabilities and favorable phase transitions in a two-dimensional (2D) spin-$1/2$ semimetal that owns a quadratic band crossing point (QBCP)…
N\'eel ordered antiferromagnets exhibit two-mode squeezing such that their ground state is a nonclassical superposition of magnon Fock states. Here we theoretically demonstrate that antiferromagnets can couple to spin qubits via direct…
The longitudinal dipole response of a quantum dot has been calculated in the far-infrared regime using local spin density functional theory. We have studied the coupling between the collective spin and density modes as a function of the…
We consider a 2-impurity Kondo system with spin-exchange coupling within the conduction band. Our numerical renormalization group calculations show that for strong intraband spin correlations the competition of these correlations with Kondo…