Frustration-induced phase transitions in the spin-S orthogonal-dimer chain

We investigate quantum phase transitions in a frustrated orthogonal-dimer chain with an arbitrary spin $S>~1/2.$ When the ratio of the competing exchange couplings is varied, first-order phase transitions occur $2S$ times among distinct spin-gap phases. The introduction of single-ion anisotropy further enriches the phase diagram. The phase transitions described by the present model possess most of the essential properties inherent in frustrated quantum spin systems.We investigate quantum phase transitions in a frustrated orthogonal-dimer chain with an arbitrary spin $S>~1/2.$ When the ratio of the competing exchange couplings is varied, first-order phase transitions occur $2S$ times among distinct spin-gap phases. The introduction of single-ion anisotropy further enriches the phase diagram. The phase transitions described by the present model possess most of the essential properties inherent in frustrated quantum spin systems.

arXiv:cond-mat/0201518Physical review. B, Condensed matterMay 30, 200221 citations

First-Order Phase Transitions in Frustrated Spin Systems

Akihisa Koga, Akira Kawaguchi, Kouichi Okunishi +1 more

We give a short review of our recent works on the first-order quantum phase transitions in frustrated spin chains with orthogonal-dimer structure. When the ratio of the competing antiferromagnetic exchange couplings is varied, a first-order transition occurs between the dimer phase and the plaquette phase, which is accompanied by the discontinuity in the spin excitation gap. We further show that strong frustration triggers the phase transitions in a magnetic field, which exhibit plateaus and jumps in the magnetization curve. The hole-doping effect is also addressed for the orthogonal-dimer chain with linked-tetrahedra structure. It is found that the competing antiferromagnetic interactions result in a firstorder metal-insulator transition upon hole doping. Recently antiferromagnetic quantum spin systems with strong frustration have been studied intensively. A typical example is SrCu2(BO3)2 1) where the spin-1/2 magnetic Cu ions are located on the orthogonal-dimer lattice (the so-called Shastry-Sutherland model). 2) Various interesting phenomena were observed for this compoundWe give a short review of our recent works on the first-order quantum phase transitions in frustrated spin chains with orthogonal-dimer structure. When the ratio of the competing antiferromagnetic exchange couplings is varied, a first-order transition occurs between the dimer phase and the plaquette phase, which is accompanied by the discontinuity in the spin excitation gap. We further show that strong frustration triggers the phase transitions in a magnetic field, which exhibit plateaus and jumps in the magnetization curve. The hole-doping effect is also addressed for the orthogonal-dimer chain with linked-tetrahedra structure. It is found that the competing antiferromagnetic interactions result in a firstorder metal-insulator transition upon hole doping. Recently antiferromagnetic quantum spin systems with strong frustration have been studied intensively. A typical example is SrCu2(BO3)2 1) where the spin-1/2 magnetic Cu ions are located on the orthogonal-dimer lattice (the so-called Shastry-Sutherland model). 2) Various interesting phenomena were observed for this compound

Jan 1, 20021 citation

We investigate quantum phase transitions in a frustrated orthogonal-dimer chain with an arbitrary spin

S>~1/2.

When the ratio of the competing exchange couplings is varied, first-order phase transitions occur

2S

times among distinct spin-gap phases. The introduction of single-ion anisotropy further enriches the phase diagram. The phase transitions described by the present model possess most of the essential properties inherent in frustrated quantum spin systems.