Spin-gap evolution upon Ca doping in the spin-ladder series Sr<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mrow><mml:mn>14</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:math>Ca<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mi>x</mml:mi></mml:msub></mml:math>Cu<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>24</mml:mn>

Deng, Guochu; Tsyrulin, N.; Bourgès, Philippe; Lamago, D.; Rønnow, Henrik M.; Kenzelmann, M.; Danilkin, Sergey; Pomjakushina, E.; Conder, K.

doi:10.1103/physrevb.88.014504

Cited by 16 publications

(24 citation statements)

References 22 publications

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“…A recent study by some of the authors of the present paper showed how the incommensurate structures of the Sr 14−x Ca x Cu 24 O 41 series evolve with the Ca doping content, which provides direct structural evidence for the charge transfer from the spin chains to the ladders by increasing Ca doping level [14]. Our inelastic neutron-scattering experiments revealed that the increase of Ca doping did not close the spin gap of the spin ladder in all these compounds, but only suppressed its intensity due to the increase of hole doping [16]. In the highly doped compound SrCa 13 Cu 24 O 41 , long-range magnetic ordering has been observed and the coexistence of magnetic ordering and a spin-liquid ground state was demonstrated [17].…”

Section: Introductionmentioning

confidence: 74%

Spin dynamics of edge-sharing spin chains in SrCa13Cu24O41

Deng

Mole

et al. 2018

Phys. Rev. B

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The low-energy magnetic excitation from the highly Ca-doped quasi-one-dimensional magnet SrCa 13 Cu 24 O 41 was studied in the magnetic ordered state by using inelastic neutron scattering. We observed the gapless spin-wave excitation, dispersive along the a and c axes but nondispersive along the b axis. Such excitations are attributed to the spin wave from the spin-chain sublattice. Model fitting to the experimental data gives the nearest-neighbour interaction J c as 5.4 meV and the interchain interaction J a = 4.4 meV. J c is antiferromagnetic and its value is close to the nearestneighbour interactions of the similar edge-sharing spin-chain systems such as CuGeO 3 . Comparing with the hole-doped spin chains in Sr 14 Cu 24 O 41 , which shows a spin gap due to spin dimers formed around Zhang-Rice singlets, the chains in SrCa 13 Cu 24 O 41 show a gapless excitation in this study. We ascribe such a change from gapped to gapless excitations to holes transferring away from the chain sublattice into the ladder sublattice upon Ca doping. IntroductionThe dimensionality of a spin system is one of the most important characters for its underlying physics. Most of the three-dimensional (3D) Heisenberg magnetic systems can be well described by the linear spin-wave theory (LSWT), which was developed decades ago 1 . Upon reducing a magnetic system from 3D to two or one dimensions (2D or 1D), quantum fluctuations will be substantially enhanced, which consequently results in various intriguing and exotic physical phenomena. 2 The theoretical work by Bethe more than 80 years ago predicted that the S = ½ antiferromagnetic Heisenberg chain cannot form a long-range magnetic ordering due to strong quantum fluctuations. 3 A domain-wall-like spin excitation called "spinon" was proposed later, which has been experimentally confirmed in various real magnetic systems. Unfortunately, except for the S = ½ spinchain case, no exact analytical solution like Bethe's work has been developed for other 1D antiferromagnetic Heisenberg spin systems. However, numerical methods were widely employed to study the ground states of more complicated 1D systems, 4 such as 1D spin chains with S > ½ and spin ladders with even/odd legs 5 , and successfully predicted their ground state and dynamic behaviours.As the simplest case of a 1D spin system, Cu 2+ (S = ½) spin chains are extensively investigated due to their close relationship with the cuprate high-temperature superconductors. 5 CuO 2 chains can be divided into two classes, corner-sharing spin chains and the edge-sharing spin chains. The former are building blocks of cuprate superconductors and spin ladders. In corner-sharing CuO 2 chains, the exchange interaction between the nearest neighbours (NN) comes from the super-exchange through the ~180 o Cu-O-Cu pathway. 6 Such an interaction is experimentally demonstrated to be quite strong, ranging from 100 meV to 160 meV. 7 In contrast, the NN exchange interaction along edge-sharing spin chains is much weaker due to the ~90 o Cu-O-Cu pathway. [8][9][10] The...

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Section: Introductionmentioning

confidence: 74%

Spin dynamics of edge-sharing spin chains in SrCa13Cu24O41

Deng

Mole

et al. 2018

Phys. Rev. B

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“…Alternatively, the divalent Sr and Ca ions can be substituted by trivalent La, which causes a drastic [140], whereas findings from nuclear magnetic resonance (NMR) experiments suggest a gradual decrease of ∆ [141][142][143][144]. It should be mentioned that the NMR findings suggest a somewhat larger ∆/k B for x = 0 (up to ∼ 650 K) than those from INS.…”

Section: Materials Aspectsmentioning

confidence: 96%

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

Heß

2019

Physics Reports

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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...

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“…However, O d2 q , see Eq. (37), implies that the two-triplon excitation signal does not vanish. Based on the scattering operator derived in this paper, we suggest that the two-triplon excitation will contribute to the direct RIXS spectrum even at the zeromomentum transfer point in the spin gap dimerized system.…”

Section: A K-edge Rixsmentioning

confidence: 99%

K -edge and L3 -edge RIXS study of columnar and staggered quantum dimer phases of the square lattice Heisenberg model

He¹,

Datta²,

Yao³

2020

Phys. Rev. B

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We compute the K and L 3 -edge resonant inelastic x-ray scattering (RIXS) spectrum of the columnar and the staggered quantum dimer states accessible to the square lattice Heisenberg magnet. Utilizing a bond operator representation mean field theory we investigate the RIXS features of the one-and two-triplon excitation spectrum supported by the quantum dimer model in the background of condensed singlet excitation. We find that the two-triplon excitation boundary lies within a 124 (78) meV to 414 (345) meV energy range for the columnar (staggered) phase. We estimated the two-triplon gap to be 124 (78) meV for the columnar (staggered) dimer phase. The highest intensity of the K -edge RIXS spectrum is centralized approximately around the (π/2, π/2) point for both the columnar and the staggered phases. At the L 3 -edge we study the one-and two-triplon signal considering experimental scattering geometry, polarization restriction, and experimental resolution effects. Our calculations find an additional contribution to the two-triplon RIXS signal, not previously reported in the literature, that originates from the local hard-core dimer constraint. This leads to a finite non-zero signal at the (0,0) momentum transfer which can offer an explanation for the existing ladder RIXS experiments and also predicts a non-zero signal for the two-dimensional quantum dimer system. We find that the L 3 edge RIXS response of the one-and two-triplon signal could exist in antiphase rung modulation for zero and π as found in inelastic neutron scattering. We also consider static crystal twinning at the L 3 -edge RIXS signal to mimic realistic crystal effects. Since the disordered phase has the potential to harbor a variety of quantum paramagnetic states, our RIXS calculations provide useful signatures to identify the true nature of the ordering pattern. PACS number(s): 78.70. Ck, 75.10.Jm

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Spin-gap evolution upon Ca doping in the spin-ladder series Sr14−xCaxCu24

Cited by 16 publications

References 22 publications

Spin dynamics of edge-sharing spin chains in SrCa13Cu24O41

Spin dynamics of edge-sharing spin chains in SrCa13Cu24O41

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

K -edge and L3 -edge RIXS study of columnar and staggered quantum dimer phases of the square lattice Heisenberg model

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