Low-temperature heat transport of spin-gapped quantum magnets

Caner

J of Applied Polymer Sci

et al. 2021

Section: Mechanical Propertiesmentioning

confidence: 64%

Section: Mechanical Propertiesmentioning

confidence: 99%

Section: Mechanical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of hetero‐armed star‐shaped PCL‐PLA polymers with POSS core on thermal, mechanical, and morphological properties of PLA

Caner

J of Applied Polymer Sci

et al. 2021

“…Intriguing heat conductivity results for one-dimensional spin systems with relatively small exchange interactions have been obtained for both organic and inorganic materials, see e.g. [32,[172][173][174][175] for S = 1/2 systems and [28,30,55,[176][177][178][179] for systems with large spin, see also the reviews [180,181].…”

Section: Discussionmentioning

confidence: 96%

Heat transport of cuprate-based low-dimensional quantum magnets with strong exchange coupling

Heß

2019

Physics Reports

Transport properties provide important access to a solid's quasiparticles, such as quasiparticle density, mobility, and scattering. The transport of heat can be particularly revealing because, in principle, all types of excitations in a solid may contribute. Heat transport is well understood for phonons and electrons, but relatively little is known about heat transported by magnetic excitations. However, during the last about two decades, the magnetic heat transport attracted increasing attention after the discovery of large and unusual signatures of it in low-dimensional quantum magnetic cuprate materials. Today it constitutes an important probe to otherwise often elusive, topological quasiparticles in a broader class of quantum magnets. This review summarizes the experimental foundation of this research, i.e. the state of the art for the magnetic heat transport in the mentioned cuprate materials which host prototypical low-dimensional antiferromagnetic S = 1/2 Heisenberg models. These comprise, in particular, the two-dimensional square lattice, and one-dimensional spin chain and two-leg ladder spin models. It is shown, how studying the heat transport provides direct access to the thermal occupation and the scattering of the already quite exotic quasiparticles of these models which range from spin-1 spin wave and triplon excitations to fractionalized spin-1/2 spinons. Remarkable transport properties of these quasiparticles have been revealed: the spin-heat transport often is highly efficient and in some cases even ballistic, in agreement with theoretical predictions. We are considering S = 1/2 models with Heisenberg interactionwhere the sum runs over all nearest neighbors in the system. Here we are investigating three different spin models: the 2D-HAF, the two-leg spin ladder, and spin chains. For the 2D-HAF and the spin chain J i,j = J and for the spin ladder J i,j = J along the legs and J i,j = J ⊥ along the rungs of the ladder. The corresponding low-dimensional quantum spin models are characterized by very peculiar ground states which are quantum disordered in the one-dimensional chain and ladder models. The elementary excitations which emerge from this ground states bear therefore a quite exotic character. For instance, the spin-spin correlations of S = 1/2 Heisenberg spin chains, decay algebraically with distance between the spins [65]. The elementary excitations are nevertheless well defined. They are fractionalized, i.e. ∆S = 1 spin-flip excitations of the system decay into so-called spinons which are gapless and carry a spin S = 1/2 [66]. On the other hand, the ground state of a two-leg ladder possesses more short-range spin-spin correlations which decay exponentially as a function of distance [67,68]. The elementary excitations are S = 1 particles (usually called magnons or triplons) and are separated from the ground state by a spin gap ∆ (∆/k B ≈ 400 K in the case of the systems discussed here) [68]. Finally, the ground state of the 2D-HAF is a rather classical longrange ordered Néel state. However, al...

Thermal conductivity of Ca3Co2O6 single crystals

Shi

et al. 2017

AIP Advances

Ca3Co2O6 is a rare example of one-dimensional Ising spin-chain material with the moments preferentially aligned along the c axis. In this work, we study the c-axis thermal conductivity (κc) of Ca3Co2O6 single crystal at low temperatures down to 0.3 K and in magnetic fields up to 14 T. The zero-field κc(T) shows a large phonon peak and can be well fitted by using the classical Debye model, which indicates that the heat transport is purely phononic. Moreover, the low-T κc(H) isotherms with H || c display a field-independent behavior. These results indicate that there is no contribution of magnetic excitations to the thermal conductivity in Ca3Co2O6, neither carrying heat nor scattering phonons, which can be attributed to the Ising-like spin anisotropy.