Magnetic and resonance properties of LiCu2O2 single crystals

Воротынов, А. М.; Pankrats, A. I.; Petrakovskiı̌, G. A.; Sablina, K. A.; Paszkowicz, W.; Szymczak, H.

doi:10.1134/1.558548

Cited by 33 publications

(21 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…13 Many early works attempted to describe LiCu 2 O 2 as an alternating Heisenberg antiferromagnetic chain and applied Bonner-Fisher fitting to the magnetic susceptibility for T Ͼ T h ; however, the fitting is generally unsatisfactory. 14,15 Later nearest-neighbor ͑nn͒ exchange coupling J 1 is found to be ferromagnetic and J 2 to be antiferromagnetic, based both on local-density approximation ͑LDA͒ calculation and neutron-scattering spin-wave analysis, which satisfies the classical spin spiral ordering requirement of ͉J 2 / J 1 ͉ Ͼ 1 4 as verified experimentally. 8,9 Quantum fluctuation must sustain in the spin spiral ordered state to account for the discrepancy found in polarized neutron-scattering intensity for this frustrated low-dimensional spin-1/2 system.…”

Section: Introductionmentioning

confidence: 63%

Nonmagnetic impurity perturbation to the quasi-two-dimensional quantum helimagnetLiCu2O2

et al. 2010

View full text Add to dashboard Cite

A complete phase diagram of Zn-substituted quantum quasi-two-dimensional helimagnet LiCu 2 O 2 has been presented. Helical ordering transition temperature ͑T h ͒ of the original LiCu 2 O 2 follows finite size scaling for less than ϳ5.5% Zn substitution, which implies the existence of finite helimagnetic domains with domain boundaries formed with nearly isolated spins. Higher Zn substitution Ն5.5% quenches the long-range helical ordering and introduces an intriguing Zn-level-dependent magnetic phase transition with slight thermal hysteresis and a universal quadratic field dependence for T c ͑ZnϾ 0.055, H͒. The magnetic coupling constants of nearest-neighbor J 1 and next-nearest-neighbor J 2 ͑␣ = J 2 / J 1 ͒ are extracted from high temperature series expansion fitting and N = 16 finite chain exact diagonalization simulation. We have also provided evidence of direct correlation between long-range helical spin ordering and the magnitude of electric polarization in this spindriven multiferroic material.

show abstract

Section: Introductionmentioning

confidence: 63%

Nonmagnetic impurity perturbation to the quasi-two-dimensional quantum helimagnetLiCu2O2

et al. 2010

View full text Add to dashboard Cite

show abstract

“…[7][8][9][10][11] This compound has an orthorhombic crystal structure of a space group Pnma with the lattice parameters a=5.72Å, b=2.86Å and c=12.4Å.…”

mentioning

confidence: 99%

Coexistence of dimerization and long-range magnetic order in the frustrated spin-chain systemLiCu2O2:Inelastic light scattering stu

et al. 2004

View full text Add to dashboard Cite

Raman scattering studies of the frustrated spin chain system LiCu2O2 are reported. Two transitions into a magnetically ordered phase (taken place at temperatures ∼ 9 K and ∼ 24 K) have been confirmed from the analysis of optical properties of the samples. Interestingly, two different magnetic excitations, seen at 100 and 110 cm −1 in the magnetically ordered phase superimpose each other independently, indicating a coherent coexistence of long-range magnetic order and dimerization. The observed phenomenon is attributed to magnetostructural peculiarities of LiCu2O2 leading to the intrinsic presence of nonmagnetic impurities on a nanometer scale. Furthermore, magnetic impurities play a significant role in driving the transition from an incommensurate state to a Néel ordered one at 9 K.Theoretical and experimental investigations of lowdimensional spin systems with frustration and dimerization have been boosted by the discovery of the inorganic spin-Peierls system CuGeO 3 .[1] Such a frustrated spin chain system shows a rich phase diagram, including both gapped and gapless phases [2], as well as disorder-induced long-range ordering, coexisting with a dimerized state.[3] Variational calculations suggest that the resonatingvalence-bond character of spin correlations at short distances can be responsible for the enhancement of antiferromagnetic (AFM) correlations near vacancies [4,5], that eventually results in long-range AFM order, locally coexisting with the disordered dimerized phase. Such a coexistence was observed in some other doped systems with reduced dimensionality (for instance, in highly holedoped chain material Sr 0.73 CuO 2 [6]) and appears to be a fundamental property of low-dimensional quantum spin systems.LiCu 2 O 2 can be regarded as a realization of a S=1/2 spin chain with competing nearest-and next-nearestneighbor interactions. [7][8][9][10][11] This compound has an orthorhombic crystal structure of a space group Pnma with the lattice parameters a=5.72Å, b=2.86Å and c=12.4Å.[7] There are monovalent and bivalent copper ions in the unit cell. Magnetic Cu 2+ ions form a double-chain along the b axis which is separated from each other by both Li ions and planes with nonmagnetic Cu + ions. The two separate Cu chains within the double-chain structure are coupled via a 90• oxygen bond along the c axis. At elevated temperatures high-field electron spin resonance (ESR) gives evidence for a spin singlet state with spin gap of ∆ ∼ 72 K.[10] Interestingly, upon cooling a spin singlet state transits into a long-range ordered state with helimagnetic structure at T c1 ∼ 24 K.[11] Some bulk measurements point to the presence of a second low temperature transition with a collinear AFM structure at T c2 ∼ 9 K.[10] Both transitions are attributed to an intrinsic non-stoichiometry and the effect of nonmagnetic and/or magnetic impurities. [10,11] However, the exact origin is not yet clear. In addition, with decreasing temperature a reduction of orthorhombic strain has been observed. [8] These magnetostructural peculiariti...

show abstract

“…For the ESR measurements they were fixed in Suprasil quartz tubes with paraffin to provide a well defined rotation axis for angular dependent investigations. The ESR measurements were performed in a Bruker ELEXSYS E500-CW spectrometer equipped with continuous-flow He cryostats (Oxford Instruments) at X-(9.47 GHz) and Q-band (34 GHz) frequencies in the temperature range 4.2 ≤ T ≤ 300 K. Like in earlier reports 23,25 and as shown in observed ESR absorption is well described by a single Lorentzian line with resonance field H res and half-width at half maximum linewidth ∆H within the whole paramagnetic range above T > 35 K. Note that the lines with the large linewidth ∆H ≈ H res were fitted including the counter resonance at −H res as described in Ref. 57.…”

Section: Resultsmentioning

confidence: 99%

“…Previous ESR experiments revealed a single exchange-narrowed Lorentz-shaped absorption line with g values g c ≈ 2.22 and g a ≈ g b ≈ 2.0 at a microwave frequency of 9 GHz and T ≫ T max as well as g c ≈ 2.29 at 227 GHz. 23,25 The ESR linewidth ∆H was found to amount more than 1 kOe at room temperature and to diverge to low temperature on approaching magnetic order with a critical behavior ∆H ∝ (T − T crit ) (−p) with T crit = 30 K and p = 1.28 or 1.35 for H||c or H ⊥ c, respectively, at 9 GHz and T crit = 23 K and p = 0.58 for H||c at 227 GHz. 23,25 So far the discussion and analysis of the paramagnetic resonance remained on a qualitative level.…”

Section: -29mentioning

confidence: 97%

See 1 more Smart Citation

Anisotropic exchange in LiCu2O2

et al. 2017

View full text Add to dashboard Cite

We investigate the magnetic properties of the multiferroic quantum-spin system LiCu2O2 by electron spin resonance (ESR) measurements at X-and Q-band frequencies in a wide temperature range (TN1 ≤ T ≤ 300 K). The observed anisotropies of the g tensor and the ESR linewidth in untwinned single crystals result from the crystal-electric field and from local exchange geometries acting on the magnetic Cu 2+ ions in the zigzag-ladder like structure of LiCu2O2. Supported by a microscopic analysis of the exchange paths involved, we show that both the symmetric anisotropic exchange interaction and the antisymmetric Dzyaloshinskii-Moriya interaction provide the dominant spin-spin relaxation channels in this material.

show abstract

Magnetic and resonance properties of LiCu2O2 single crystals

Cited by 33 publications

References 16 publications

Nonmagnetic impurity perturbation to the quasi-two-dimensional quantum helimagnetLiCu2O2

Nonmagnetic impurity perturbation to the quasi-two-dimensional quantum helimagnetLiCu2O2

Coexistence of dimerization and long-range magnetic order in the frustrated spin-chain systemLiCu2O2:Inelastic light scattering stu

Anisotropic exchange in LiCu2O2

Contact Info

Product

Resources

About