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Metamagnetic quantum criticality in Sr3Ru2O7 studied by thermal expansion.
P Gegenwart1, F Weickert, M Garst
1Max-Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany.
Physical Review Letters
|May 23, 2006
Summary
Low-temperature measurements reveal entropy accumulation in strontium ruthenium oxide (Sr3Ru2O7) near 8 Tesla, linked to a quantum critical point. This point is obscured by metamagnetic transitions, but thermal expansion aligns with itinerant theory predictions.
Area of Science:
- Condensed matter physics
- Materials science
Background:
- Sr3Ru2O7 is a bilayer ruthenate material exhibiting complex electronic properties.
- Quantum critical points (QCPs) are fundamental in understanding emergent phenomena in correlated electron systems.
Purpose of the Study:
- To investigate the low-temperature thermal expansion of Sr3Ru2O7 under a perpendicular magnetic field.
- To identify the role of entropy accumulation and quantum criticality in the material's metamagnetic transitions.
Main Methods:
- Low-temperature thermal expansion measurements.
- Application of magnetic fields perpendicular to the ruthenium-oxide planes.
Main Results:
- Observed field dependence of the c-axis expansion coefficient indicates entropy accumulation near 8 Tesla.
- Two first-order metamagnetic transitions were identified, masking an underlying quantum critical point.
- A region of enhanced entropy was found bounded by these transitions.
Conclusions:
- The thermal expansion behavior outside the transition region is consistent with predictions for a two-dimensional metamagnetic quantum critical endpoint.
- The study provides insights into the interplay between metamagnetism, entropy, and quantum criticality in Sr3Ru2O7.