Spin wave analysis of heisenberg magnets in restricted geometries

Ivanov, N. B.; Sen, Diptiman

doi:10.1007/bfb0119594

Cited by 9 publications

(13 citation statements)

References 79 publications

(214 reference statements)

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“…AFM systems with disordered ground states, such as the AFM wheels, represent a challenge for any SWT since these start by construction from an ordered ground state. As a result, the energies of the Goldstone modes are obtained as zero even in finite spin systems, and divergencies appear, e.g., in the magnetization (which actually can be used as an indication of the absence of order in the considered spin model 43,44 ). Linear and interacting SWTs (LSWT and ISWT) are typical representatives.…”

Section: Discussionmentioning

confidence: 98%

Discrete antiferromagnetic spin-wave excitations in the giant ferric wheel Fe18

et al. 2012

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The low-temperature elementary spin excitations in the AFM molecular wheel Fe 18 were studied experimentally by inelastic neutron scattering and theoretically by modern numerical methods, such as dynamical density matrix renormalization group or quantum Monte Carlo techniques, and analytical spin-wave theory calculations. Fe 18 involves eighteen spin-5/2 Fe III ions with a Hilbert space dimension of ∼10 14 , constituting a physical system that is situated in a region between microscopic and macroscopic. The combined experimental and theoretical approach allowed us to characterize and discuss the magnetic properties of Fe 18 in great detail. It is demonstrated that physical concepts such as the rotational-band or L and E-band concepts developed for smaller rings are still applicable. In particular, the higher-lying low-temperature elementary spin excitations in Fe 18 or AFM wheels, in general, are of discrete antiferromagnetic spin-wave character.

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Section: Discussionmentioning

confidence: 98%

Discrete antiferromagnetic spin-wave excitations in the giant ferric wheel Fe18

et al. 2012

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“…The corre-sponding correction can be calculated using the standard approach [19][20][21] and in our case has the form…”

Section: ͑16͒mentioning

confidence: 99%

Excitation spectra of hard-core bosons on square and triangular lattices in superfluid phase

et al. 2010

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Excitation spectra of hard-core bosons with nearest-and next-nearest-neighbor interactions on square and triangular lattices in the superfluid phase are studied using the spin-wave theory. We go beyond the standard linear spin-wave approximation calculating corrections due to spin-wave interaction. Account for the spinwave interaction considerably improves the quantitative description of the excitation spectra. The behavior of the spectra is analyzed in detail at different particle densities and relations between the interaction parameters. Particular attention is given to the spectrum minima with the aim to find out the conditions for instability of the superfluid phase. We show that for a triangular lattice at high enough next-nearest-neighbor repulsion there appears a true roton minimum inside the Brillouin zone located on the line connecting the zone center with the midpoint of the face of the zone boundary. The obtained analytical results are in excellent quantitative agreement with the numerical simulations known from literature.

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“…Such ferrimagnetic ground states may also be referred to as quantized ferrimagnetic states since the FM moment is quantized in integral (or half-integral) multiples of the number of unit cells L. As explicitly demonstrated below (section 3), strong enough competing interactions can suspend this quantization rule in some regions of the parameter space where the long-range ferrimagnetic order still survives. Since the model has a magnetically ordered ground state, this makes the 1D problem amenable to the spin-wave theory (SWT) approach [17].…”

Section: H =mentioning

confidence: 99%

Spin models of quasi-1D quantum ferrimagnets with competing interactions

Ivanov¹

2009

Condens. Matter Phys.

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We present a brief survey of the recent theoretical work related to generic Heisenberg spin models describing quasi-one-dimensional quantum ferrimagnets. The emphasis is on quantum chains and ladders with strong competing interactions, such as the frustrated J 1 − J 2 chain with alternating (1, 1/2) spins, the spin-1/2 diamond chain with four-spin cyclic couplings, and some generic types of mixed-spin ladders with geometric frustration. As a rule, the discussed models exhibit rich quantum phase diagrams and provide some interesting examples of one-dimensional magnetic-paramagnetic quantum phase transitions. A number of open problems in the reviewed research area are discussed.

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Spin wave analysis of heisenberg magnets in restricted geometries

Cited by 9 publications

References 79 publications

Discrete antiferromagnetic spin-wave excitations in the giant ferric wheel Fe18

Discrete antiferromagnetic spin-wave excitations in the giant ferric wheel Fe18

Excitation spectra of hard-core bosons on square and triangular lattices in superfluid phase

Spin models of quasi-1D quantum ferrimagnets with competing interactions

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