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Magnetic-field-controlled spin fluctuations and quantum critically in Sr3Ru2O7
C Lester1, S Ramos2, R S Perry3
1H.H. Wills Physics Laboratory, University of Bristol, Tyndall Ave., Bristol, BS8 1TL, UK.
Nature Communications
|October 5, 2021
Summary
Quantum criticality in Sr3Ru2O7 is linked to spin fluctuations. These fluctuations explain strange metal behavior and are key to the spin-density-wave phase, revealing an "order-by-disorder" mechanism.
Area of Science:
- Condensed Matter Physics
- Quantum Materials
- Quantum Critical Phenomena
Background:
- Quantum critical points emerge when continuous phase transitions are tuned to absolute zero.
- Strontium ruthenate (Sr3Ru2O7) exhibits quantum criticality tunable by magnetic fields at low temperatures.
- Near its critical field (Bc), Sr3Ru2O7 displays characteristics of strange metals, including T-linear resistivity and specific heat behavior.
Purpose of the Study:
- To investigate the role of critical fluctuations in the strange metal behavior of Sr3Ru2O7 near quantum criticality.
- To establish a quantitative link between spin fluctuations and the enhanced electronic heat capacity and entropy observed near Bc.
- To elucidate the mechanism stabilizing the spin-density-wave ordered phase.
Main Methods:
- Inelastic neutron scattering was employed to probe collective spin fluctuations in Sr3Ru2O7.
- Measurements were conducted as a function of magnetic field near the critical field Bc.
- Analysis focused on the relaxation time and strength of spin fluctuations and their correlation with thermodynamic properties.
Main Results:
- Collective spin fluctuations were observed with relaxation times and strengths that vary significantly near Bc.
- The observed increase in electronic heat capacity and entropy near Bc was quantitatively explained by electron scattering from these spin fluctuations.
- Spin fluctuations strengthen upon entering the spin-density-wave ordered phase.
Conclusions:
- Collective spin fluctuations are directly responsible for the strange metal behavior in Sr3Ru2O7 near quantum criticality.
- The spin-density-wave order is stabilized by these fluctuations via an "order-by-disorder" mechanism.
- This study provides a quantitative link between spin dynamics and emergent electronic properties at quantum critical points.
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