Properties of YbAgCu{sub 4} at high pressures and magnetic fields
Journal Article
·
· Physical Review, B: Condensed Matter
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
We have measured the electrical resistivity of YbAgCu{sub 4} at quasihydrostatic pressures to 190 kbar and in magnetic fields to 8 T. At ambient pressure, YbAgCu{sub 4} is weakly mixed valent and has a Sommerfeld coefficient of specific heat {gamma} of approximately 240 mJ/mole K{sup 2}. With applied pressure, the ground-state degeneracy is reduced from eightfold to twofold degenerate as the energy scale {ital T}{sub 0} characterizing the strongly correlated electron system is reduced from 130 to {similar_to}0.9 K at 190 kbar and {gamma} is estimated to increase to approximately 4900 mJ/mole K{sup 2}. At intermediate pressures {ital T}{sub 0} and crystal-field splittings are comparable, which accounts for the lack of resistive scaling at these pressures. Systematics in the pressure-dependent resistivity suggest that YbAgCu{sub 4} should order magnetically at pressures not far above 190 kbar. The ``residual resistivity`` {rho}{sub 0} of YbAgCu{sub 4} increases dramatically with decreasing volume due to resonant scattering of heavy quasiparticles by lattice defects. At high pressures and low temperatures the magnetoresistance is large and negative and has the field dependence expected of a spin-1/2 Kondo impurity. The pressure and field dependences of {rho}{sub 0} and the {ital T}{sup 2} coefficient of resistivity raise the question of their functional relationship and how we are to understand impuritylike behavior in a band of strongly correlated quasiparticles.
- OSTI ID:
- 83929
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 5 Vol. 52; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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