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Quantum phase transitions of magnetic rotons
Jörg Schmalian1, Misha Turlakov
1Department of Physics and Astronomy and Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA.
Physical Review Letters
|August 25, 2004
Summary
Magnetic rotons, arising from broken symmetry, drive quantum phase transitions in itinerant ferromagnets. These magnetic rotons explain the unusual high-pressure behavior observed in systems like MnSi.
Area of Science:
- Condensed matter physics
- Quantum magnetism
Background:
- Paramagnons in itinerant ferromagnetic systems are influenced by weak spin-orbit coupling and broken inversion symmetry.
- These conditions can lead to the emergence of magnetic rotons.
Purpose of the Study:
- Investigate quantum phase transitions driven by fluctuations in systems with magnetic rotons.
- Explore the role of anisotropy in controlling quantum tricritical points.
- Characterize non-Fermi liquid behavior linked to magnetic rotons.
Main Methods:
- Self-consistent Hartree calculations
- Renormalization group calculations
Main Results:
- Identified magnetic rotons as key excitations in itinerant ferromagnets.
- Characterized weak fluctuation-driven first-order quantum phase transitions.
- Revealed a quantum tricritical point influenced by anisotropy.
- Observed non-Fermi liquid behavior associated with a large phase volume of magnetic rotons.
Conclusions:
- Magnetic rotons are crucial for understanding the anomalous high-pressure behavior of itinerant helical ferromagnets like MnSi.
- The theoretical framework provides insights into quantum phase transitions and exotic electronic states.
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