Pressure effect on the valence transition of EuNi{sub 2}(Ge{sub 1{minus}x}Si{sub x}){sub 2}
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
The temperature dependence of electrical resistivity {rho} has been measured for EuNi{sub 2}(Ge{sub 1{minus}x}Si{sub x}){sub 2} with 0.0{le}x{le}0.15 at pressures to 15 kbar. At ambient pressure, all the compounds are antiferromagnetic with stable Eu{sup 2+} moments, but compounds with 0.10{le}x{le}0.15 show a pressure-induced valence transition. Just above a critical pressure, the compound undergoes a first-order valence transition. With further increase in pressure, the valence transition becomes continuous. The temperature dependence of {rho} is discussed by regarding the system as a virtual alloy of Eu{sub p{sub 2}}{sup 2+}Eu{sub p{sub 3}}{sup 3+}, where p{sub 2} and p{sub 3} are the occupation probabilities of Eu{sup 2+} and Eu{sup 3+} states, respectively. We argue that impurity scattering due to randomness in a virtual alloy is responsible for the temperature dependence of {rho} in this system. By combining the present results with previous determinations of the pressure dependence of the tetragonal unit-cell volume, a generalized pressure-temperature phase diagram of EuNi{sub 2}Ge{sub 2} is established which indicates that applying pressure is equivalent to Si doping in EuNi{sub 2}Ge{sub 2}. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 289184
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 2 Vol. 59; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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