Related papers: Emergent Anti-ferromagnetism in a Y -Shaped Kekul\…
We study the competition of spin- and charge-density waves and their quantum multicritical behavior for the semimetal-insulator transitions of low-dimensional Dirac fermions. Employing the effective Gross-Neveu-Yukawa theory with two order…
We study the quantum critical properties of antiferromagnetism in graphene at T=0 within mean-field (MF) theory. The resulting exponents differ from the conventional MF exponents, describing finite temperature transitions. Motivated by…
We use determinant quantum Monte Carlo (DQMC) simulations to study the role of electron-electron interactions on three-dimensional (3D) Dirac fermions based on the $\pi$-flux model on a cubic lattice. We show that the Hubbard interaction…
The interplay between localized magnetic moments and itinerant electrons gives rise to exotic quantum states in condensed matter systems. Two-dimensional moire superlattices offer a powerful platform for engineering heavy fermion states…
We use the determinant Quantum Monte Carlo method (DQMC) to study the interaction-driven semimetal to antiferromagnetic insulator transition in a $\pi$-flux Hamiltonian with modulated hoppings, a model which has two species of Dirac…
In this paper we discuss the N$\acute{e}$el and Kekul$\acute{e}$ valence bond solids quantum criticality in graphene Dirac semimetal. Considering the quartic four-fermion interaction $g(\bar{\psi}_i\Gamma_{ij}\psi_j)^2$ that contains…
Motivated by the recent experiment of Velasco Jr. {\em et al.} [J. Velasco Jr. {\em et al.}, Nat. Nanotechnology 7, {\bf 156} (2012)], we develop a mean-field theory of the interaction-induced antiferromagnetic (AF) state in bilayer…
It is generally believed that free-standing graphene does not demonstrate any ferroic properties. In the present work we revise this statement and show that single graphene sheet with a pair of magnetic adatoms can be driven into…
The ability to localize and manipulate individual quasiparticles in mesoscopic structures is critical in experimental studies of quantum mechanics and thermodynamics, and in potential quantum information devices, e.g., for topological…
Magnetic properties of graphene with randomly distributed magnetic defects/vacancies are studied in terms of the Kondo Hamiltonian in the mean field approximation. It has been shown that graphene with defects undergoes a magnetic phase…
The Gross-Neveu-Heisenberg universality class describes a continuous quantum phase transition between a Dirac semimetal and an antiferromagnetic insulator. Such quantum critical points have originally been discussed in the context of…
Our previous results on the nonperturbative calculations of the mean current and of the energy-momentum tensor in QED with the T-constant electric field are generalized to arbitrary dimensions. The renormalized mean values are found; the…
We establish a scenario where fluctuations of new degrees of freedom at a quantum phase transition change the nature of a transition beyond the standard Landau-Ginzburg paradigm. To this end we study the quantum phase transition of gapless…
We study a quantum phase transition from a massless to massive Dirac fermion phase in a new two-dimensional bipartite lattice model of electrons that is amenable to sign-free quantum Monte Carlo simulations. Importantly, interactions in our…
Motivated by the physics of graphene, we consider a model of N species of 2+1 dimensional four-component massless Dirac fermions interacting through a 3D instantaneous Coulomb interaction. We show that in the limit of infinitely strong…
An $S=1/2$ ferromagnetic (F) - antiferromagnetic (AF) random alternating Heisenberg quantum spin chain model is investigated in connection to its realization compound: (CH$_3$)$_2$CHNH$_3$Cu(Cl$_x$Br$_{1-x}$)$_3$. The exchange interaction…
We consider a model of Dirac fermions in $2+1$ dimensions with dynamically generated, anticommuting SO(3) N\'eel and Z$_2$ Kekul\'e mass terms that permits sign-free quantum Monte Carlo simulations. The phase diagram is obtained from…
Kekul\'{e}-ordered graphene on SiC realized by intercalating two-dimensional metal layers offers a versatile platform for exploring intriguing quantum states and phenomena. Here, we achieve the intercalation of…
A deformation of a graphene sheet changes more than the positions of the atoms. In the low-energy Dirac theory it also produces geometric electron-phonon vertices. One of these vertices acts as an emergent phonon gauge field, $\calA_\mu$,…
We present the first results of numerical simulations of a 2+1 dimensional fermion field theory based on a recent proposal for a model of graphene, consisting of N_f four-component Dirac fermions moving in the plane and interacting via an…