Neutron scattering study of two-magnon states in the quantum magnet copper nitrate

Tennant, A.; Broholm, C.; Reich, Daniel H.; Nagler, S. E.; Granroth, G. E.; Barnes, T.; Damle, Kedar; Xu, Gang; Chen, Y.; Sales, B. C.

doi:10.1103/physrevb.67.054414

Cited by 60 publications

(65 citation statements)

References 29 publications

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“…3, are in quantitative agreement with the interacting two-particle Schrödinger wave functions, calculated in the appendix of Ref. 19. In particular, we resolve the spin-1 bound mode of the AHC, which is a direct signature of the two-particle interaction, given in Figs.…”

Section: A One-magnon Two-magnon and Bound Statessupporting

confidence: 72%

“…23 Equivalent chains lie along the [1,1,1]/2 and [1,−1,1]/2 directions and project onto the same direction on the (h,0,l) plane. 19 A dilution insert provided sample temperatures down to 120 mK and a rotation stage allowed the magnetic chains to be rotated to different angles relative to the incident beam of neutrons. A white beam is pulsed at 50 Hz with neutrons arriving at the sample over the initial 34-m flight path at different times according to their energy.…”

Section: B Neutron Scatteringmentioning

confidence: 99%

“…The nearest-neighbor potential V s is −J /2,−J /4,J /4 for pairs with combined total spin s = 0,1,2, respectively, and provides an attraction that has important effects on multiparticle states. There are two types of solutions to the two-particle Schrödinger equation: 19 The first has the form of a continuum of states, where k 1 and k 2 are momenta of the magnons along the chain, with total momentum along the chain Q = k 1 + k 2 and energyhω = hω(k 1 ) +hω(k 2 ). The scattering matrix (S matrix) describing the interchange of two particles in a state with total spin s is given by S s k1,k2 , and the corresponding phase shift is φ s k1,k2 = −(i/2) ln(S s k1,k2 ).…”

Section: Theorymentioning

confidence: 99%

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Anomalous dynamical line shapes in a quantum magnet at finite temperature

et al. 2012

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The effect of thermal fluctuations on the dynamics of a gapped quantum magnet is studied using inelastic neutron scattering on copper nitrate, a model material for the spin-1/2, one-dimensional (1D) bond alternating Heisenberg chain. A large, highly deuterated, single-crystal sample of copper nitrate is produced using a solution growth method and measurements are made using the high-resolution backscattering spectrometer OSIRIS at the ISIS Facility. Theoretical calculations and numerical analysis are combined to interpret the physical origin of the thermal effects observed in the magnetic spectra. The primary observations are (1) a thermally induced central peak due to intraband scattering, which is similar to Villain scattering familiar from soliton systems in 1D, and (2) the one-magnon quasiparticle pole is seen to develop with temperature into an asymmetric continuum of scattering. We relate this asymmetric line broadening to a thermal strongly correlated state caused by hard-core constraints and quasiparticle interactions. These findings are a counter example to recent assertions of the universality of line broadening in 1D systems and are applicable to a broad range of quantum systems.

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Section: A One-magnon Two-magnon and Bound Statessupporting

confidence: 72%

Section: B Neutron Scatteringmentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

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Anomalous dynamical line shapes in a quantum magnet at finite temperature

et al. 2012

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“…Because of coupling between dimers, triplons usually become mobile and can hop to neighboring dimer sites. For particular cases, the thermodynamic finite temperature behavior of the mobility of these hard-core bosons has been treated using statistical models reproducing triplon band renormalization and damping observed in experiments [5][6][7][8][9]. In general, the increase of the thermal population of bosons produces an increased repulsion and a reduced mobility, which is observed as a reduction of the dispersion bandwidth.…”

mentioning

confidence: 99%

Correlated Decay of Triplet Excitations in the Shastry-Sutherland CompoundSrCu2(BO3)2
Zayed
¹
,
Rüegg
²
,
Strässle
³

et al. 2014
Phys. Rev. Lett.
19
2
19
0
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The temperature dependence of the gapped triplet excitations (triplons) in the 2D Shastry-Sutherland quantum magnet SrCu 2 ðBO 3 Þ 2 is studied by means of inelastic neutron scattering. The excitation amplitude rapidly decreases as a function of temperature, while the integrated spectral weight can be explained by an isolated dimer model up to 10 K. Analyzing this anomalous spectral line shape in terms of damped harmonic oscillators shows that the observed damping is due to a two-component process: one component remains sharp and resolution limited while the second broadens. We explain the underlying mechanism through a simple yet quantitatively accurate model of correlated decay of triplons: an excited triplon is long lived if no thermally populated triplons are nearby but decays quickly if there are. The phenomenon is a direct consequence of frustration induced triplon localization in the Shastry-Sutherland lattice. Quantum spin systems display a wide range of intriguing many-body quantum effects. A particularly active field is the study of interacting dimer systems. Two antiferromagnetically coupled spins forming a dimer have a singlet ground state with an energy gap to excited triplet states. In extended systems where dimers couple to each other, the ground state often remains a spin singlet and gapped. The excitations are known as triplons and can be described in terms of quasiparticles as hard-core bosons [1][2][3][4]. Because of coupling between dimers, triplons usually become mobile and can hop to neighboring dimer sites. For particular cases, the thermodynamic finite temperature behavior of the mobility of these hard-core bosons has been treated using statistical models reproducing triplon band renormalization and damping observed in experiments [5][6][7][8][9]. In general, the increase of the thermal population of bosons produces an increased repulsion and a reduced mobility, which is observed as a reduction of the dispersion bandwidth. The theoretical treatment of finite temperature damping, reflecting the lifetime of the boson and the related spectral functions, remains an ongoing challenge [10][11][12][13].The compound SrCu 2 ðBO 3 Þ 2 constitutes an important example for testing our understanding of quantum spin systems, as it is a close realization of the frustrated but "exactly solvable" 2D Shastry-Sutherland model [14,15] (see Refs. [16,17] for a review). In SrCu 2 ðBO 3 Þ 2 , triplons are prevented from hopping already at zero temperature by frustrated interdimer interactions. Despite the strong (frustrated) coupling, the triplon dispersion is very shallow. Theoretical studies show that hopping is allowed only from the sixth order in the inter-to intradimer coupling ratio J 0 =J or in the presence of Dzyaloshinskii-Moriya (DM) terms. It has, however, been shown that multiple triplons forming a bound state are more mobile than a single triplon due to correlated hopping processes, appearing already in second order in J 0 =J [16,18]. In high magnetic fields, triplons in SrCu 2 ðBO 3 Þ 2 crystalliz...

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“…Using conventional INS it has been shown that copper nitrate [Cu(NO 3 ) 2 × 2.5 D 2 O], a model material for a onedimensional alternating Heisenberg chain (AHC), displays a temperature dependent asymmetric lineshape in the frequency domain [9,23,24]. The material was recently investigated in the time domain using the high resolution neutron resonance spin-echo triple-axis spectroscopy (NRSE-TAS) [25].…”

Section: Introductionmentioning

confidence: 99%

Time-dependent correlations in quantum magnets at finite temperature

et al. 2016

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In this Rapid Communication we investigate the time dependence of the gap mode of copper nitrate at various temperatures. We combine state-of-the-art theoretical calculations with high precision neutron resonance spin-echo measurements to understand the anomalous decoherence effects found previously in this material. It is shown that the time domain offers a complementary view on this phenomenon, which allows us to directly compare experimental data and theoretical predictions without the need of further intensive data analysis, such as (de)convolution.

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Neutron scattering study of two-magnon states in the quantum magnet copper nitrate

Cited by 60 publications

References 29 publications

Anomalous dynamical line shapes in a quantum magnet at finite temperature

Anomalous dynamical line shapes in a quantum magnet at finite temperature

Correlated Decay of Triplet Excitations in the Shastry-Sutherland CompoundSrCu2(BO3)2
Zayed
¹
,
Rüegg
²
,
Strässle
³

et al. 2014
Phys. Rev. Lett.
19
2
19
0
View full text Add to dashboard Cite

Time-dependent correlations in quantum magnets at finite temperature

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Neutron scattering study of two-magnon states in the quantum magnet copper nitrate

Cited by 60 publications

References 29 publications

Anomalous dynamical line shapes in a quantum magnet at finite temperature

Anomalous dynamical line shapes in a quantum magnet at finite temperature

Correlated Decay of Triplet Excitations in the Shastry-Sutherland CompoundSrCu2(BO3)2Zayed1, Rüegg2, Strässle3 et al. 2014Phys. Rev. Lett.192190View full textAdd to dashboardCite

Time-dependent correlations in quantum magnets at finite temperature

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Correlated Decay of Triplet Excitations in the Shastry-Sutherland CompoundSrCu2(BO3)2
Zayed
¹
,
Rüegg
²
,
Strässle
³

et al. 2014
Phys. Rev. Lett.
19
2
19
0
View full text Add to dashboard Cite