Effects of disorder and isotopic substitution in the specific heat and Raman scattering in LuB{sub 12}

Journal Article · Thu Sep 15 04:00:00 EDT 2011 · Journal of Experimental and Theoretical Physics

DOI:https://doi.org/10.1134/S1063776111080103· OSTI ID:22028020

Azarevich, A N; Bogach, A V; Vlasov, I I; Glushkov, V V; Demishev, S V ^[1]; Maksimov, A A; Tartakovskii, I I; Filatov, E V ^[2]; Flachbart, K; Gabani, S ^[3]; Filippov, V B; Shitsevalova, N Yu ^[4]; Moshchalkov, V V ^[5]

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1. Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)
2. Russian Academy of Sciences, Institute of Solid State Physics (Russian Federation)
3. Slovak Academy of Sciences, Institute of Experimental Physics (Slovakia)
4. National Academy of Sciences of Ukraine, Institute of Problems of Materials Science (Ukraine)
5. Katholieke Universiteit Leuven, Institute of Nanoscale Physics and Chemistry (Belgium)

Precision measurements of the specific heat and spectral intensity I({omega}) of Raman scattering for Lu{sup N}B{sub 12} single crystal samples with various boron isotopes (N = 10, 11, nat) have been performed at low and intermediate temperatures. A boson peak in the low-frequency part of the I({omega}) spectrum has been observed for the first time for lutetium dodecaboride at liquid nitrogen temperatures. It has been shown that low-temperature anomalies in the specific heat, along with the features of Raman spectra, can be interpreted in terms of the transition to a cageglass state at T* = 50-70 K, which appears when Lu{sup 3+} ions are displaced from the centrosymmetric position in cavities of a rigid covalent boron sublattice towards the randomly located boron vacancies. The concentrations of various two-level systems that correspond to two types of vibrational clusters with correlation lengths of 12-15 and 18-22 A, respectively, have been estimated. The vibrational density of states of LuB{sub 12} has been calculated from Raman spectra in the model of soft atomic potentials. An approach has been proposed to explain the dielectrization of the properties of the YbB{sub 12} compound at T < T*, as well as the features of the formation of magnetic structures in RB{sub 12} antiferromagnets (R = Tb, Dy, Ho, Er, Tm) and the suppression of superconductivity in LuB{sub 12}.

• OSTI ID: 22028020
• Journal Information: Journal of Experimental and Theoretical Physics, Journal Name: Journal of Experimental and Theoretical Physics Journal Issue: 3 Vol. 113; ISSN JTPHES; ISSN 1063-7761
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIFERROMAGNETIC MATERIALS
ANTIFERROMAGNETISM
BORON
BORON ISOTOPES
CORRELATIONS
COVALENCE
ISOTOPIC EXCHANGE
LUTETIUM
LUTETIUM BORIDES
LUTETIUM IONS
MONOCRYSTALS
RAMAN SPECTRA
SPECIFIC HEAT
SUPERCONDUCTIVITY
VACANCIES