Magnetism and electronic correlations in quasi-one-dimensional compounds

Abstract

Nesta contribuição à celebração do octogésimo aniversário de nascimento do Prof. Ricardo Ferreira, apresentamos uma breve discussão sobre compostos magnéticos quase-unidimensionais. Esta tem sido uma área de pesquisa de intensa atividade, particularmente após a divulgação de verificações experimentais de magnetismo em polímeros organometálicos na década de 1980. Neste trabalho realizamos uma revisão das contribuições teóricas e experimentais sobre o assunto, com foco em sistemas de elétrons correlacionados em cadeias com célula unitária do tipo AB 2 presentes em compostos inorgânicos e orgânicos.In this contribution on the celebration of the 80th birthday anniversary of Prof. Ricardo Ferreira, we present a brief survey on the magnetism of quasi-one-dimensional compounds. This has been a research area of intense activity particularly since the first experimental announcements of magnetism in organic and organometallic polymers in the mid 80's. We review experimental and theoretical achievements on the field, featuring chain systems of correlated electrons in a special AB 2 unit cell structure present in inorganic and organic compounds.

Magnetic and nonmagnetic phases in dopedAB2 t−JHubbard chains

“…Further, the inclusion of competing interactions or geometrical and kinetic frustration [19][20][21], enlarge the classes of models, thereby allowing ground-states not obeying Lieb or Lieb and Mattis theorems. These studies have proved effective in describing magnetic and other physical properties of a variety of organic, organometallic, and inorganic quasione-dimensional compounds [19,22].…”

Frustration-induced quantum phase transitions in a quasi-one-dimensional ferrimagnet: Hard-core boson map and the Tonks-Girardeau limit

“…In this work we introduce an isotropic Heisenberg spin Hamiltonian with two competing antiferromagnetic (AF) exchange couplings [J 1 (≡ 1) and J] exhibiting a continuous quantum phase transition at a critical value J c1 which, we argue, is a superfluid-insulator transition (SIT) of magnons associated with the creation of a coherent superposition of singlet and triplet states at lattice unit cells. For J = 0, the model shares its phenomenology and unit cell topology with quasi-one-dimensional ferrimagnetic compounds [9], such as the line of trimer clusters present in copper phosphates [10], and the organic ferrimagnet PNNBNO (Ref. [11]).…”

Lieb and hole-doped ferrimagnetism, spiral, resonating valence-bond states, and phase separation in large-U AB 2 Hubbard chains

“…Much attention has been given to quantum phase transitions [1,2], which are phenomena characterized by the change of the nature of the ground state (GS) driven by a non-thermal parameter: pressure, magnetic field, doping, Coulomb repulsion, or competitive interactions. In this context, the study of quasi-one-dimensional (quasi-1D) compounds with ferrimagnetic properties [3,4] has attracted considerable theoretical and experimental interest because of their unique physical properties and very rich phase diagrams. In particular, the GS of quasi-1D quantum ferrimagnets with AB 2 or ABB unit cell topologies (diamond or trimer chains) described by the Heisenberg or Hubbard models [5] exhibit unsaturated spontaneous magnetization, ferromagnetic and antiferromagnetic spin-wave modes, effect of quantum fluctuations, and fielddependent magnetization plateaus, among several other features of interest.…”