Effects of disorder and isotopic substitution in the specific heat and Raman scattering in LuB12

Sluchanko, N. E.; Azarevich, A. N.; Bogach, A. V.; Власов, И. И.; Ġlushkov, V. V.; Demishev, S. V.; Максимов, А. А.; Tartakovskii, I. I.; Filatov, E. V.; Flachbart, К.; Gabáni, S.; Филиппов, В. Б.; Shitsevalova, N. Yu.; Moshchalkov, Victor

doi:10.1134/s1063776111080103

Cited by 63 publications

(63 citation statements)

References 64 publications

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“…The spectra observed with 633 nm (1.96 eV) laser excitation ( Fig.2A) are very similar to ones measured in 18 . The low-temperature continuum near 185 cm −1 in these spectra shifts to higher energies and broadens with increasing temperature.…”

Section: Raman Results and Calculationssupporting

confidence: 80%

Raman study of coupled electronic and phononic excitations in LuB12

Ponosov

Махнев

Streltsov

et al. 2017

Journal of Alloys and Compounds

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Electronic Raman scattering and optical phonon self-energies are studied on single crystals of LuB12 with different isotopic composition in the temperature region 10-650K and at pressures up to 10 GPa. The shape and energy position of the spectral peaks depend on the magnitude of the probed wave vector, temperature, and symmetry of excitations. We simulated experimental spectra using electronic structure obtained in the density function theory and taking into account the electron-phonon scattering. The emergence of a broad continuum in the spectra is identified with the inelastic scattering of light from the electronic intraband excitations. Their coupling to non-fully symmetric phonon modes is the source of both the Fano interference and temperature-dependent phonon self-energies. In addition, long wavelength vibrations of the boron atoms are in nonadiabatic regime, so the electronic contribution to their self-energies provides a temperature dependence that is similar to the anharmonic contribution. Comparison of calculation and experiment allowed us to determine the coupling constant λep=0.32, which gives correct critical temperature of the transition to the superconducting state.

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Section: Raman Results and Calculationssupporting

confidence: 80%

Raman study of coupled electronic and phononic excitations in LuB12

Ponosov

Махнев

Streltsov

et al. 2017

Journal of Alloys and Compounds

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“…Note that the defect mode contribution of LaB 6 may also be estimated from data presented in [4,5]. Moreover, the existence of TLS was experimentally detected from the recent Raman spectra investigations of LuB 12 [11], which is a nonmagnetic analog of LaB 6 . The detailed analysis of specic heat of LaB 6 will be presented elsewhere.…”

Section: Resultsmentioning

confidence: 92%

Defect Mode in LaB_{6}

et al. 2014

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The specic heat of high quality La N B6 (N = 10, 11, natural) single crystals is investigated in a wide range of temperatures 2 300 K. The obtained data allow to estimate correctly (i) the electronic γ · T term of specic heat (γ ≈ 2.4 mJ/(mol·K 2 )), (ii) the contribution from quasilocal vibrating mode of La 3+ ions (ΘE ≈ 150 152 K), (iii) the Debye-type term from rigid boron cages (ΘD ≈ 1160 ± 40 K). Our data also suggest an additional defectmode component (iv) which may be attributed to a contribution of 1.5% boron vacancies in LaB6. The obtained results may be interpreted in terms of formation of two level systems, which appear when La 3+ ions are displaced from their centrosymmetric positions in the cavities of rigid boron cages, apart from randomly distributed boron vacancies in the LaB6 matrix.

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“…As promising materials for the study of negative MR effect we have chosen the fcc metallic substitutional solid solutions Ho x Lu 1−x B 12 with Ho magnetic ions embedded in a rigid covalent boron cage of the dodecaboride lattice. Comprehensive investigations of high-quality single crystals of LuB 12 with various boron isotope compositions allowed recently finding a new disordered "cage-glass" phase at liquid nitrogen temperatures [38][39][40]. It was shown [39,40] 12 with magnetic rare-earth ions, there is also Lu to Ho substitutional disorder which interferes with the random displacements (static disorder) of R sites in the metallic cage-glass phase.…”

Section: Introductionmentioning

confidence: 97%

Charge transport inHoxLu1−xB12: Separating positive and negative magnetoresistance in metals with magnetic ions

Sluchanko

Khoroshilov²,

Anisimov³

et al. 2015

Phys. Rev. B

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The magnetoresistance (MR) ρ/ρ of the cage-glass compound Ho x Lu 1−x B 12 with various concentrations of magnetic holmium ions (x 0.5) has been studied in detail concurrently with magnetization M(T ) and Hall effect investigations on high-quality single crystals at temperatures 1.9-120 K and in magnetic field up to 80 kOe. The undertaken analysis of ρ/ρ allows us to conclude that the large negative magnetoresistance (nMR) observed in the vicinity of the Néel temperature is caused by scattering of charge carriers on magnetic clusters of Ho 3+ ions, and that these nanosize regions with antiferromagnetic (AF) exchange inside may be considered as short-range-order AF domains. It was shown that the Yosida relation − ρ/ρ ∼ M 2 provides an adequate description of the nMR effect for the case of Langevin-type behavior of magnetization. Moreover, a reduction of Ho-ion effective magnetic moments in the range 3-9 μ B was found to develop both with temperature lowering and under the increase of holmium content. A phenomenological description of the large positive quadratic contribution ρ/ρ ∼ μ 2 D H 2 which dominates in Ho x Lu 1−x B 12 in the intermediate temperature range 20-120 K allows us to estimate the drift mobility exponential changes μ D ∼ T −α with α = 1.3-1.6 depending on Ho concentration. An even more comprehensive behavior of magnetoresistance has been found in the AF state of Ho x Lu 1−x B 12 where an additional linear positive component was observed and attributed to charge-carrier scattering on the spin density wave (SDW). High-precision measurements of ρ/ρ = f (H,T ) have allowed us also to reconstruct the magnetic H-T phase diagram of Ho 0.5 Lu 0.5 B 12 and to resolve its magnetic structure as a superposition of 4f (based on localized moments) and 5d (based on SDW) components.

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Effects of disorder and isotopic substitution in the specific heat and Raman scattering in LuB12

Cited by 63 publications

References 64 publications

Raman study of coupled electronic and phononic excitations in LuB12

Raman study of coupled electronic and phononic excitations in LuB12

Defect Mode in LaB_{6}

Charge transport inHoxLu1−xB12: Separating positive and negative magnetoresistance in metals with magnetic ions

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