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Magnetic fluctuations at a field-induced quantum phase transition
O Stockert1, M Enderle, H V Löhneysen
1Max-Planck-Institut für Chemische Physik fester Stoffe, D-01187 Dresden, Germany.
Physical Review Letters
|February 1, 2008
Summary
We studied magnetic quantum phase transitions in CeCu5.8Au0.2 using neutron scattering. Our findings support a spin-density-wave scenario over a local quantum critical point, revealing distinct quantum fluctuation spectra.
Area of Science:
- Condensed Matter Physics
- Quantum Materials Science
- Magnetism
Background:
- Quantum phase transitions (QPTs) are fundamental phenomena in condensed matter physics, driven by quantum fluctuations at absolute zero temperature.
- Tuning parameters like magnetic field or chemical composition can induce QPTs, leading to changes in material properties.
- Understanding the nature of quantum fluctuations is crucial for characterizing different QPT scenarios.
Purpose of the Study:
- To investigate the field-induced magnetic quantum phase transition in CeCu5.8Au0.2.
- To compare the applicability of spin-density-wave (SDW) and local quantum critical point (QCP) scenarios to this transition.
- To provide microscopic evidence for differences in quantum fluctuation spectra based on tuning parameters.
Main Methods:
- Inelastic neutron scattering (INS) was employed to probe the magnetic excitations.
- The experimental data was analyzed and compared against theoretical models for different QPT scenarios.
Main Results:
- The inelastic neutron-scattering data for CeCu5.8Au0.2 at its field-induced magnetic quantum phase transition were better described by the spin-density-wave (SDW) scenario.
- In contrast, the local quantum critical point (QCP) scenario was previously found applicable to the concentration-tuned QPT in CeCu6-xAux (x=0.1).
Conclusions:
- This study provides direct microscopic evidence distinguishing between different quantum fluctuation spectra at magnetic quantum critical points.
- The findings highlight that the nature of quantum criticality in cerium intermetallic compounds depends significantly on the tuning parameter (field vs. concentration).
- The results contribute to a deeper understanding of the complex physics governing quantum phase transitions in strongly correlated electron systems.
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