Hall and transverse even effects in the vicinity of a quantum critical point in Tm{sub 1-x}Yb{sub x}B{sub 12}

Journal Article · Sat Sep 15 00:00:00 EDT 2012 · Journal of Experimental and Theoretical Physics

DOI:https://doi.org/10.1134/S1063776112090130· OSTI ID:22069337

Azarevich, A N; Bogach, A V; Glushkov, V V; Demishev, S V; Anisimov, M A ^[1]; Levchenko, A V; Filipov, V B; Shitsevalova, N Yu ^[2]

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1. Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)
2. National Academy of Sciences of Ukraine, Frantsevich Institute for Problems of Materials Science (Ukraine)

The angular, temperature, and magnetic field dependences of the resistance recorded in the Hall effect geometry are studied for the rare-earth dodecaboride Tm{sub 1-x}Yb{sub x}B{sub 12} solid solutions where the metal-insulator and antiferromagnetic-paramagnetic phase transitions are observed in the vicinity of the quantum critical point x{sub c} Almost-Equal-To 0.3. The measurements performed on high-quality single crystals in the temperature range 1.9-300 K for the first time have revealed the appearance of the second harmonic contribution, a transverse even effect in these fcc compounds near the quantum critical point. This contribution a is found to increase drastically both under the Tm-to-ytterbium substitution in the range x > x{sub c} and with an increase in the external magnetic field. Moreover, as the Yb concentration x increases, a negative peak of a significant amplitude appears on the temperature dependences of the Hall coefficient R{sub H}(T) for the Tm{sup 1-x}Yb{sub x}B{sub 12} compounds, in contrast to the invariable behavior R{sub H}(T) Almost-Equal-To const found for TmB{sub 12}. The complicated activation-type behavior of the Hall coefficient is observed at intermediate temperatures for x {>=} 0.5 with activation energies E{sub g}/k{sub B} Almost-Equal-To 200 K and E{sub a}/k{sub B} 55-75 K, and the sign inversion of R{sub H}(T) is detected at liquid-helium temperatures in the coherent regime. Renormalization effects in the electron density of states induced by variation of the Yb concentration are analyzed. The anomalies of the charge transport in Tm{sub 1-x}Yb{sub x}B{sub 12} solid solutions in various regimes (charge gap formation, intra-gap many-body resonance, and coherent regime) are discussed in detail and the results are interpreted in terms of the electron phase separation effects in combination with the formation of nanosize clusters of rare earth ions in the cage-glass state of the studied dodecaborides. The data obtained allow concluding that the emergence of Yb-Yb dimers in the Tm{sub 1-x}Yb{sub x}B{sub 12} cage-glass matrix is the origin of the metal-insulator transition observed in the achetypal strongly correlated electron system of YbB{sub 12}.

• OSTI ID: 22069337
• Journal Information: Journal of Experimental and Theoretical Physics, Vol. 115, Issue 3; Other Information: Copyright (c) 2012 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7761
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTIVATION ENERGY
ANTIFERROMAGNETISM
CHARGE TRANSPORT
DIMERS
ELECTRON CORRELATION
ELECTRON DENSITY
FCC LATTICES
GLASS
HALL EFFECT
MAGNETIC FIELDS
MANY-BODY PROBLEM
MATRIX MATERIALS
MONOCRYSTALS
NANOSTRUCTURES
PARAMAGNETISM
PHASE TRANSFORMATIONS
SOLID SOLUTIONS
TEMPERATURE DEPENDENCE
THULIUM BORIDES
YTTERBIUM BORIDES