Singlet ground-state fluctuations in praseodymium observed by muon spin relaxation in PrP and PrP0.9
| Autor: | C. E. Stronach, D. R. Noakes, G. M. Kalvius, M. F. White Jr., Roger Wäppling |
|---|---|
| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Journal of Physics: Condensed Matter. 17:119-136 |
| ISSN: | 1361-648X 0953-8984 |
| Popis: | Muon spin relaxation (µSR) in the singlet ground-state compounds PrP and PrP0.9 reveals the unusual situation of a Lorentzian local field distribution with fast-fluctuation-limit strong-collision dynamics, a case that does not show motional narrowing. Contrary to publications by others, where PrP0.9 was asserted to have vacancy-induced spin-glass freezing, no spin-glass freezing is seen in PrP0.9 or PrP down to . This was confirmed by magnetization measurements on these same samples. In both compounds, the muon spin relaxation rate does increase as temperature decreases, demonstrating increasing strength of the paramagnetic response. A Monte Carlo model of fluctuations of Pr ions out of their crystalline-electric-field singlet ground states into their magnetic excited states (and back down again) produces the strong-collision-dynamic Lorentzian relaxation functions observed at each individual temperature but not the observed temperature dependence. This model contains no exchange interaction, and so predicts decreasing paramagnetic response as the temperature decreases, contrary to the temperature dependence observed. Comparison of the simulations to the data suggests that the exchange interaction is causing the system to approach magnetic freezing (by mode softening), but fails to complete the process. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|