Semiclassical approach to competing orders in a two-leg spin ladder with ring exchange

Totsuka, Keisuke; Lecheminant, P.; Capponi, Sylvain

doi:10.1103/physrevb.86.014435

Cited by 12 publications

(4 citation statements)

References 69 publications

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“…correlations of spin-quadrupole moments (and in some cases, higher-order spin-multipoles), in frustrated ferromagnetic spin chains [10][11][12][13][14][15][16][17][18][19][20][21][22][23] , in spin-1/2 ladders with cyclic exchange 24,25 and for spin-1 models with biquadratic interactions [26][27][28] .…”

Section: Introductionmentioning

confidence: 99%

Theory of spin excitations in a quantum spin-nematic state

2013

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The idea that a quantum magnet could act like a liquid crystal, breaking spin-rotation symmetry without breaking time-reversal symmetry, holds an abiding fascination. However, the very fact that spin nematic states do not break time-reversal symmetry renders them "invisible" to the most common probes of magnetism -they do not exhibit magnetic Bragg peaks, a static splitting of lines in NMR spectra, or oscillations in µSR. Nonetheless, as a consequence of breaking spin-rotation symmetry, spin-nematic states do possess a characteristic spectrum of dispersing excitations which could be observed in experiment. With this in mind, we develop a symmetry-based description of long-wavelength excitations in a spin-nematic state, based on an SU(3) generalisation of the quantum non-linear sigma model. We use this field theory to make explicit predictions for inelastic neutron scattering, and argue that the wave-like excitations it predicts could be used to identify the symmetries broken by the otherwise unseen spin-nematic order.

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Section: Introductionmentioning

confidence: 99%

Theory of spin excitations in a quantum spin-nematic state

2013

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“…19,20 The relevance of the four-spin cyclic exchange has also been reported [21][22][23][24][25][26][27][28][29] in the frame of inelastic neutron-scattering experiments for cuprates such as La 2 CuO 4 , La 6 The model (1) in the N = 2 case has been studied extensively over the years by means of different analytical and numerical approaches. [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] The zero-temperature phase diagram is rich and several exotic phases have been identified such as a scalar chirality phase which spontaneously breaks the time-reversal symmetry. 31 When J ⊥ > 0, the ring exchange destabilizes the well-known rung-singlet (RS) phase of the standard two-leg spin ladder and a staggered dimerization (SD) phase emerges.…”

Section: Introductionmentioning

confidence: 99%

Quantum phase transitions in multileg spin ladders with ring exchange

2013

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Four-spin exchange interaction has been raising intriguing questions regarding the exotic phase transitions it induces in two-dimensional quantum spin systems. In this context, we investigate the effects of a cyclic four-spin exchange in the quasi-1D limit by considering a general N-leg spin ladder. We show by means of a low-energy approach that, depending on its sign, this ring exchange interaction can engender either a staggered or a uniform dimerization from the conventional phases of spin ladders. The resulting quantum phase transition is found to be described by the SU(2)_N conformal field theory. This result, as well as the fractional value of the central charge at the transition, is further confirmed by a large-scale numerical study performed by means of Exact Diagonalization and Density Matrix Renormalization Group approaches for N \le 4

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“…and ε αβγ is the Levi-Civita symbol. We note that the Hamiltonian keeps the SU(2) symmetry of triplets 38,45,46 , as far as the magnetic field is not applied 47 .…”

Section: B Effective Hamiltonianmentioning

confidence: 99%

Multiple quadrupolar or nematic phases driven by the Heisenberg interactions in a spin-1 dimer system forming a bilayer

Hotta

2020

Phys. Rev. B

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Spin nematics had long been considered as an elusive nonmagnetic state, where the spin-1 moments lose their directions while keeping the orientations in a spatially ordered manner similar to the liquid crystals. Such order emerges as a result of transverse fluctuation of spin-1 moments, which is enhanced by the quantum many body effect. We propose a realistic model system based on dimers forming bilayers that can easily host spin nematics. Each dimer consists of antiferromagnetically coupled spin-1 pair which tend to form a dimer-singlet phase. We show that this dimer-singlet is immediately replaced with the ferroic nematic phases, when very small inter-dimer Heisenberg exchange interactions are introduced. This nematics is exotic in the sense that the spin-1 moments form a uniform Bose-Einstein condensate, whereas the nematic directors develop a spatially modulated structure. It apparently differs from the conventional ones found in a strong magnetic field or next to the ferromagnetic phases, which were often difficult to realize in experiments. Hidden nematic phases should thus exist in many of the quantum spin-dimer materials, which serve as a good platform to study nematic phases in laboratories, and a family of Ba3ZnRu2O9 may become a first possible example. arXiv:1909.04647v1 [cond-mat.str-el]

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Semiclassical approach to competing orders in a two-leg spin ladder with ring exchange

Cited by 12 publications

References 69 publications

Theory of spin excitations in a quantum spin-nematic state

Theory of spin excitations in a quantum spin-nematic state

Quantum phase transitions in multileg spin ladders with ring exchange

Multiple quadrupolar or nematic phases driven by the Heisenberg interactions in a spin-1 dimer system forming a bilayer

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