Anomalous thermal decoherence in a quantum magnet measured with neutron spin echo spectroscopy

Groitl, Felix; Keller, T.; Rolfs, Katharina; Tennant, A.; Habicht, K.

doi:10.1103/physrevb.93.134404

Cited by 7 publications

(28 citation statements)

References 41 publications

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“…For the sake of brevity only a brief introduction will be given to the method itself, and we refer for the detailed description to the literature [25,[38][39][40][41][42][43]. Neutron spin-echo measures the polarization of the neutron beam P = σ x , which is called the echo amplitude.…”

Section: Experiment: Neutron Spin-echo Spectroscopymentioning

confidence: 99%

“…The experiments described in Ref. [25] have been carried out at the NRSE-TAS spectrometer TRISP [26] at the FRM II.…”

Section: Experiment: Neutron Spin-echo Spectroscopymentioning

confidence: 99%

“…1 in Ref. [25]) is used to split the two states [40] by a relative time delay τ , the so-called spin-echo time. The spin states scatter at the sample at times t and t + τ , where τ is identical to the van-Hove correlation time [41].…”

Section: Experiment: Neutron Spin-echo Spectroscopymentioning

confidence: 99%

“…The material was recently investigated in the time domain using the high resolution neutron resonance spin-echo triple-axis spectroscopy (NRSE-TAS) [25]. The advantage of NRSE-TAS [26,27] is that it gives access to slow processes corresponding to energies in the μeV range, which are not accessible by conventional INS.…”

Section: Introductionmentioning

confidence: 99%

“…In a previous study of the material [25], the experimental results in the time domain were analyzed by fitting it to a phenomenological formula [9]. This formula models an asymmetric lineshape in the frequency domain and was used to compare NRSE-TAS and ToF data to demonstrate the capabilities of NRSE-TAS.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Experiment: Neutron Spin-echo Spectroscopymentioning

confidence: 99%

“…The experiments described in Ref. [25] have been carried out at the NRSE-TAS spectrometer TRISP [26] at the FRM II.…”

Section: Experiment: Neutron Spin-echo Spectroscopymentioning

confidence: 99%

Section: Experiment: Neutron Spin-echo Spectroscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Time-dependent correlations in quantum magnets at finite temperature

et al. 2016

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Neutron Spin‐Echo Instrumentation for Magnetic Scattering

Keller

Trepka

Habicht

et al. 2021

Physica Status Solidi (b)

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Neutron spin‐echo (NSE) spectroscopy is a powerful tool for the study of magnon lifetimes and magnetic critical dynamics. The unique property of NSE is the energy resolution in the μeV range. The first NSE spectrometers were optimized for quasielastic scattering at small momentum transfers and delivered substantial contributions to the understanding of critical dynamics in ferromagnets and dynamic correlations in spin glasses. The subsequent resonant NSE (NRSE) technique extends the parameter range toward large momentum and energy transfers and permits to measure magnon lifetimes across the Brillouin zone. NRSE also comprises the Larmor diffraction (LD) mode with a resolution for lattice spacings and their variance Δdhkl/dhkl of order 10−6. LD proves useful to determine magnetostriction effects, small lattice distortions related to magnetic ordering, mosaic spread in crystals, and the size distribution of antiferromagnetic domains. Both typical experiments and the related technical innovation are reviewed and an outlook on future developments is given.

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Evidence for strong correlations at finite temperatures in the dimerized magnet Na2Cu2TeO6

et al. 2021

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Dimerized magnets forming alternating Heisenberg chains exhibit quantum coherence and entanglement and thus can find potential applications in quantum information and computation. However, magnetic systems typically undergo thermal decoherence at finite temperatures. Here, we show inelastic neutron scattering results on an alternating antiferromagnetic-ferromagnetic chain compound Na 2 Cu 2 TeO 6 that the excited quasiparticles can counter thermal decoherence and maintain strong correlations at elevated temperatures. At low temperatures, we observe clear dispersive singlet-triplet excitations arising from the dimers formed along the crystalline b axis. The excitation gap is of ∼18 meV and the bandwidth is about half of the gap. The band top energy has a weak modulation along the [100] direction, indicative of a small interchain coupling. The gap increases while the bandwidth decreases with increasing temperature, leading to a strong reduction in the available phase space for the triplons. As a result, the Lorentzian-type energy broadening becomes highly asymmetric as the temperature is raised. These results are associated with a strongly correlated state resulting from hard-core constraint and quasiparticle interactions. We consider these results to be not only evidence for strong correlations at finite temperatures in Na 2 Cu 2 TeO 6 , but also for the universality of the strongly correlated state in a broad range of quantum magnetic systems.

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Anomalous thermal decoherence in a quantum magnet measured with neutron spin echo spectroscopy

Cited by 7 publications

References 41 publications

Time-dependent correlations in quantum magnets at finite temperature

Time-dependent correlations in quantum magnets at finite temperature

Neutron Spin‐Echo Instrumentation for Magnetic Scattering

Evidence for strong correlations at finite temperatures in the dimerized magnet Na2Cu2TeO6

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