Related papers: BCS-BEC crossover in a $(t_{2g})^4$ Excitonic Magn…
Theoretical studies recently predicted the condensation of spin-orbit excitons at momentum $q$=$\pi$ in $t_{2g}^4$ spin-orbit coupled three-orbital Hubbard models at electronic density $n=4$. In parallel, experiments involving iridates with…
We study the BCS-BEC crossover phenomenon of triplet exciton condensation using a half-filled bilayer Hubbard model. We calculate the dynamical spin structure factor and the exciton wave function on the phase boundary between the…
The electronic properties of excitonic insulators have been examined precisely in recent years. Pictures of exciton condensation may be applied to the spin-state transition observed in perovskite cobalt oxides. We examine the crystal-field…
Based on a realistic spin Hamiltonian for a frustrated quasi-two dimensional spin-1/2 antiferromagnet Cs$_{2}$CuCl$_{4}$, a three-dimensional spin ordering in the applied magnetic field $B$ near the saturation value $B_{c}$ is studied…
Bose-Einstein condensation (BEC) of triplet excitations triggered by a magnetic field, sometimes called magnon BEC, in dimerized antiferromagnets gives rise to a long-range antiferromagnetic order in the plane perpendicular to the applied…
Bose-Einstein condensation of electron-hole pairs, exciton condensation, has been effortfully investigated since predicted 60 years ago. Irrefutable evidence has still been lacking due to experimental difficulties in verifying the…
Motivated by recent experiments on Ba$_{3}$Cr$_{2}$O$_8$, a new spin-dimer compound with spin-1/2 moments of Cr$^{5+}$ ions, we theoretically investigate the field-induced magnetic ordering in this material in view of the Bose-Einstein…
Motivated by recent experiments on Mott insulators, in both iridates and ultracold atoms, we theoretically study the effects of magnetic order on the Mott-Hubbard excitons. In particular, we focus on spin-mediated doublon-holon pairing in…
Single crystals of the spin dimer system Sr3Cr2O8 have been grown for the first time. Magnetization, heat capacity, and magnetocaloric effect data up to 65 T reveal magnetic order between applied fields of Hc1 ~ 30.4 T and Hc2 ~ 62 T. This…
We consider quantum phase transitions in a system of bright dipolar excitons which can form bound pairs (dipolar biexcitons). We assume a narrow resonance in the interaction of excitons with opposite spins. At sufficiently large density a…
The competition between spin-orbit coupling $\lambda$ and electron-electron interaction $U$ leads to a plethora of novel states of matter, extensively studied in the context of $t_{2g}^4$ and $t_{2g}^5$ materials, such as ruthenates and…
An asymmetric multi-quantum state magnetic lattice is proposed to host excitons formed in a quantum degenerate gas of ultracold fermionic atoms to simulate Bose-Einstein condensation (BEC) of excitons. A Quasi-two dimensional degenerate gas…
We propose experiments to observe Bose-Einstein condensation (BEC) and superfluidity of quasi-two-dimensional (2D) spatially indirect magnetoexcitons in bilayer graphene. The magnetic field $B$ is assumed strong. The energy spectrum of…
A theoretical model is developed for treating super conductive Bose-Einstein condensation (BEC) effects for excitons in planar systems, under the condition that many excitons are included in a surface area, with the dimensions of the…
We study the conditions to realize an excitonic condensed phase in an electron-hole bilayer system with local Hubbard-like interactions at half-filling, where we can address the interplay with Mott localization. Using Dynamical Mean-Field…
Using the Density Matrix Renormalization Group technique we study the effect of spin-orbit coupling on a three-orbital Hubbard model in the $(t_{2g})^{4}$ sector and in one dimension. Fixing the Hund coupling to a robust value compatible…
Macroscopic quantum coherence emerges when bosons condense into a Bose-Einstein condensate (BEC). First observed as a single-component superfluid in helium, BECs later emerged in ultracold atomic gases at nanokelvin temperatures as weakly…
Identifying materials hosting an excitonic insulator ground state has been one of the major pursuits in condensed matter physics in recent years. Promising candidates in transition metal chalcogenide compounds (TMC), including…
We use the LDA+U method to study the possibility of exciton condensation in perovskites of transition metals with $d^6$ electronic configuration such as LaCoO$_3$. For realistic interaction parameters we find several distinct solutions…
We study the superconducting transition in a two-dimensional electron gas with strong Rashba spin-orbit coupling. We assume low electron density, such that only the majority spin band participates in the transition. We show that the…