Dynamics of linarite: Observations of magnetic excitations

Rule, K. C.; Willenberg, Benjamin; Schäpers, M.; Wolter, A. U. B.; Büchner, B.; Drechsler, S.‐L.; Ehlers, Georg; Tennant, A.; Mole, Richard A.; Gardner, J. S.; Süllow, S.; Nishimoto, Sei‐ichi

doi:10.1103/physrevb.95.024430

Cited by 27 publications

(53 citation statements)

References 51 publications

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“…Any discussion of linarite in the context of purely isotropic J 1 −J 2 chain model [11,12] is incomplete. Magnetic anisotropy certainly plays a role in this material, as evidenced by the dramatic difference in the phase diagrams measured for field applied parallel and perpendicular to the chain axis [13,14].…”

Section: Introductionmentioning

confidence: 99%

Magnetic phase diagram of the strongly frustrated quantum spin chain system PbCuSO4(OH)2 in tilted magnetic fields

Feng¹,

Povarov²,

Zheludev³

2018

Phys. Rev. B

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We report the H−T phase diagram of S = 1/2 strongly frustrated anisotropic spin chain material linarite PbCuSO4(OH)2 in tilted magnetic fields up to 10 T and temperatures down to 0.2 K. By means of torque magnetometry we investigate the phase diagram evolution as the magnetic field undergoes rotation in ba * and bc planes. The key finding is the robustness of the high field spin density wave-like phase, which may persist even as the external field goes orthogonal to the chain direction b. In contrast, the intermediate collinear antiferromagnetic phase collapses at moderate deflection angles with respect to b axis. * povarovk@phys.ethz.ch † http://www.neutron.ethz.ch/ a J 1 J 2

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Section: Introductionmentioning

confidence: 99%

Magnetic phase diagram of the strongly frustrated quantum spin chain system PbCuSO4(OH)2 in tilted magnetic fields

Feng¹,

Povarov²,

Zheludev³

2018

Phys. Rev. B

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“…A similar argument can be applied to linarite, PbCu(SO 4 )(OH) 2 , that also features buckled copper chains with an intermediate Cu-Cu distance of 2.823Å. Indeed, its J 1 −8.6 K [68] or −13.8 K [69] is smaller in magnitude than in Li 2 CuO 2 , but still on the ferromagnetic side.…”

Section: Direct Exchangementioning

confidence: 72%

Origin of up-up-down-down magnetic order in Cu2GeO4

2019

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We use density-functional band-structure calculations to explore the origin of the up-up-downdown (UUDD) magnetic order in Cu2GeO4 with the frustrated J1 − J2 spin chains coupled into layers within the spinel-like crystal structure. In contrast to earlier studies, we find that the nearestneighbor coupling J1 may be negligibly small, owing to a nearly perfect compensation of the ferromagnetic direct exchange and antiferromagnetic superexchange. Under this condition, weak symmetric anisotropy of the exchange couplings gives rise to the UUDD order observed experimentally and also elucidates the non-trivial ordering pattern between the layers, whereas a small Dzyaloshinsky-Moriya interaction causes a spin canting that may generate local electric polarization. We argue that the buckling of the copper chains plays a crucial role in the suppression of J1 in Cu2GeO4 and sets this compound apart from other J1 − J2 chain magnets. I. INTRODUCTIONCopper oxides built by chains of edge-sharing CuO 4 plaquettes serve as material prototypes of frustrated spin-1 2 chains with competing nearest-neighbor and nextnearest-neighbor interactions J 1 and J 2 , respectively. This simple spin model received ample attention [1] triggered by the prospects of chiral, multipolar, and spinnematic phases that may occur therein [2][3][4][5][6][7][8]. Whereas long-range order does not take place in one dimension (1D), interchain couplings in real materials will usually cause three-dimensional (3D) collinear or noncollinear order depending on the J 2 /J 1 ratio. On the classical level, incommensurate spiral order appears for J 2 /|J 1 | > 1 4 , whereas at J 2 /|J 1 | < 1 4 the second-neighbor coupling is not strong enough to tilt the spins, and the collinear ferromagnetic or up-down-up-down antiferromagnetic order form depending on the sign of J 1 . Quantum effects preserve the spiral state in the case of ferromagnetic (FM) J 1 [9], but destroy the order and open a spin gap for antiferromagnetic (AFM) J 1 at J 2 /J 1 > 0.241 [10][11][12].Real-world prototypes of the J 1 − J 2 spin chains will typically follow one of these scenarios. The majority of quasi-1D copper oxides reveal J 2 /|J 1 | > 1 4 with FM J 1 and develop the incommensurate spiral order [13][14][15][16]. Li 2 CuO 2 [17,18] and CuAs 2 O 4 [19] are notable exceptions, where J 1 is also FM, but J 2 /|J 1 | < 1 4 renders spin alignment along the chains purely ferromagnetic. Spin-chain compounds with AFM J 1 are more rare, although tentative indications of the spin-gap formation at J 2 /J 1 > 0.241 have been reported [20].One puzzling case in this series is Cu 2 GeO 4 [21] that reveals an unanticipated antiferromagnetic up-up-downdown (UUDD) order [22] despite the prediction of FM J 1 * altsirlin@gmail.com and AFM J 2 , both of the same magnitude [23]. This parameter regime would normally lead to the incommensurate spiral order, similar to LiCuVO 4 , CuCl 2 , and other J 1 − J 2 cuprates. Here, we address this discrepancy and first analyze whether additional terms beyond J 1 and J 2 could...

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“…A second aspect that distinguishes linarite from a trivial phonon conductor is the magnetic heat transport channel that is present in phase I given by the anisotropic enhancement of κ compared to the polarized phase. INS measurements have shown that the dispersion at 0 T differs for the two axes b and c [12]. Along the chain direction, two minima at ±0.2π/a and a crossing of the branches at 0π/a were observed.…”

Section: B Magnon Transportmentioning

confidence: 97%

“…Due to the spacial separation of these strips along a and c it can be described as a quasi-1D spin chain with S = 1 2 . The magnetic interaction between the spins has been modeled based on different experimental results (neutron scattering [12], magnetic susceptibility [13,14]) which render competing exchange interactions between nearest neighbors (J 1 ≈ −78 K) and next-nearest neighbors (J 2 ≈ 28 K) [12]. Additional finite interchain couplings lead to long range magnetic order below T N = 2.8 K where the spins are arranged in an helical incommensurate state with the propagation vector q = (0; 0.186; 0.5) [15].…”

Section: Introductionmentioning

confidence: 99%

Thermal transport of the frustrated spin-chain mineral linarite: Magnetic heat transport and strong spin-phonon scattering

Gillig,

Hong,

Sakrikar

et al. 2021

Preprint

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The mineral linarite (PbCuSO4(OH)2) forms a monoclinic structure where a sequence of Cu(OH)2 units forms a spin-1 2 chain. Competing ferromagnetic nearest-neighbor (J1) and antiferromagnetic next-nearest-neighbor interactions (J2) in this quasi-one-dimensional spin structure imply magnetic frustration and lead to magnetic ordering below TN = 2.8 K in a mutliferroic elliptical spin-spiral ground state. Upon the application of a magnetic field along the spin-chain direction, distinct magnetically ordered phases can be induced. We studied the thermal conductivity κ in this material across the magnetic phase diagram as well as in the paramagnetic regime in the temperature ranges 0.07-1 K and 9-300 K. We found that in linarite the heat is carried mainly by phonons but shows a peculiar non-monotonic behavior in field. In particular, κ is highly suppressed at the magnetic phase boundaries, indicative of strong scattering of the phonons off critical magnetic fluctuations. Even at temperatures far above the magnetically ordered phases, the phononic thermal conductivity is reduced due to scattering off magnetic fluctuations. The mean free path due to spin-phonon scattering (l spin-phonon ) was determined as function of temperature. A power law behavior was observed mainly above 500 mK indicating the thermal activation of spin fluctuations. In the critical regime close to the saturation field, l spin-phonon shows a 1/T dependence. Furthermore, a magnon thermal transport channel was verified in the helical magnetic phase. We estimate a magnon mean free path which corresponds to about 1000 lattice spacings.

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Dynamics of linarite: Observations of magnetic excitations

Cited by 27 publications

References 51 publications

Magnetic phase diagram of the strongly frustrated quantum spin chain system PbCuSO4(OH)2 in tilted magnetic fields

Magnetic phase diagram of the strongly frustrated quantum spin chain system PbCuSO4(OH)2 in tilted magnetic fields

Origin of up-up-down-down magnetic order in Cu2GeO4

Thermal transport of the frustrated spin-chain mineral linarite: Magnetic heat transport and strong spin-phonon scattering

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