Quantum spin-orbital liquids are elusive strongly correlated states of matter that emerge from quantum frustration between spin and orbital degrees of freedom. A promising route towards the observation of those states is the creation of artificial Mott insulators where antiferromagnetic correlations between spins and orbitals can be designed. We show that Coulomb impurity lattices on the surface of gapped honeycomb substrates, such as graphene on SiC, can be used to simulate SU(4) symmetric spin-orbital lattice models. We exploit the property that massive Dirac fermions form mid-gap bound states with spin and valley degeneracies in the vicinity of a Coulomb impurity. Due to electronic repulsion, the antiferromagnetic correlations of the impurity lattice are driven by a super-exchange interaction with SU(4) symmetry, which emerges from the bound states degeneracy at quarter filling. We propose that quantum spin-orbital liquids can be engineered in artificially designed solid-state systems at vastly higher temperatures than achievable in optical lattices with cold atoms. We discuss the experimental setup and possible scenarios for candidate quantum spin-liquids in Coulomb impurity lattices of various geometries.
Forest fire can change the eco-stoichiometric characteristics of forest ecosystem elements, reflect the biogeochemical cycle change mode of forest ecosystem environment after fire, and clarify the eco-stoichiometric characteristics of carbon (C), nitrogen (N), phosphorus (P) in forest ecosystem under forest fire disturbance, which is very important for understanding the response mechanism of forest ecosystem to forest fire disturbance. By consulting a large number of relevant literatures, the author summarized and analyzed the impact mode of forest fire disturbance on the C–N–P eco-stoichiometric characteristics of forest ecosystem, as well as the impact of forest fire disturbance on the C–N–P eco-stoichiometric characteristics of plants, C–N–P eco-stoichiometric characteristics of litter, and C–N–P eco-stoichiometric characteristics of soil. It is considered that the C–N–P eco-stoichiometric characteristics of forest ecosystem are mainly affected by fire factors (fire intensity, fire frequency, recovery time after fire), vegetation types and soil properties. In view of the scientific problems that forest fire urgently needs to be solved in the study of forest ecosystem eco-stoichiometry, three aspects: the impact mechanism of forest fire disturbance on the homeostasis of plant eco-stoichiometry, the study of multi-element eco-stoichiometry under forest fire disturbance, the establishment of the eco-chemometrics relationship of the plant–litter–soil composite system under the interference of forest fire are proposed, in order to deeply understand the plant regulation strategy under the interference of forest fire, clarify the mutual coupling mechanism between multiple chemical elements after the interference of forest fire, and improve the relationship between the input and output of aboveground and underground nutrients with the plant–litter–soil as a composite whole, which is of great significance for a deep understanding of the nutrient cycle and balance of the forest ecosystem under the background of global climate change, and reasonable formulation of forest fire management measures.
We address the possible emergence of spin triplet superconductivity in CrO2 bilayers, which are half-metals with fully spin-polarized conducting bands. Starting from a lattice model, we show that chiral p + ip states compete with non-chiral p-wave ones. At large doping, the p + ip channel has a sequence of topological phase transitions that can be tuned by gating effects and interaction strength. Among several phases, we find chiral topological phases having a single Majorana mode at the edge. We show that different topological superconducting phases could spontaneously emerge in the vicinity of the van-Hove singularities of the band.
We investigate the effect of electron-electron interactions in ABC stacked graphene trilayers. In the gapless regime, we show that the self-energy corrections lead to the renormalization of the of dynamical exponent z = 3 + α1/N , with α1 ≈ 0.52 and N is the number of fermionic species. Although the quasiparticle residue is suppressed near the neutrality point, the lifetime has a sublinear scaling with the energy and the quasiparticles are well defined even at zero energy. We calculate the renormalization of a variety of physical observables, which can be directly measured in experiments. Introduction. In graphene single layers, the honeycomb arrangement of the carbon atoms leads to a linear electronic dispersion and to quasiparticles that behave as massless Dirac fermions, akin to massless neutrinos in quantum electrodynamics (QED) [1,2]. In graphene multilayers, the electronic spectrum varies depending on the stacking sequence. In the single particle picture, rombohedral ABC-stacked trilayer graphene reveals a gapless band structure of chiral quasiparticles with Berry phase 3π and cubic low energy excitation spectrum [3,4]. Because of the scaling of the kinetic energy, Coulomb interactions are relevant operators in the renormalization group (RG) sense, and can strongly renormalize different physical quantities. Different spontaneous broken symmetry ground states have been already proposed for trilayer graphene [5][6][7]. Very recently, transport experiments revealed a robust many-body gap of ∼40 meV at temperatures below T c ∼ 34K [8].In this letter we study the effect of Coulomb interactions and polarization effects on the behavior of the quasiparticles at small but finite temperature, when the many-body gap is zero. We investigate the analytical structure of the polarization bubble and the leading selfenergy corrections due to dynamically screened Coulomb interactions. In the gapless regime, we show that the dynamical critical exponent is renormalized to
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