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Elastic stiffness of the nuclear-spin system in tetragonal U2D2 nuclear-ordered solid (3)He.
M Yamaguchi1, S Sasaki, S G Lee
1Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Physical Review Letters
|October 4, 2003
Summary
We measured sound velocity in solid Helium-3 (³He) and found it changes with temperature due to nuclear spin interactions. These findings reveal insights into the material
Area of Science:
- Condensed matter physics
- Quantum materials research
- Low-temperature physics
Background:
- Solid Helium-3 (³He) exhibits complex phases at low temperatures.
- Nuclear ordering in solid ³He influences its physical properties.
- Understanding spin dynamics is crucial for quantum materials.
Purpose of the Study:
- To investigate the temperature dependence of sound velocity in nuclear-ordered U2D2 solid ³He.
- To determine the elastic properties related to nuclear spin interactions.
- To analyze the spin wave velocity and its Grüneisen constants.
Main Methods:
- Measurements of longitudinal and transverse sound velocity along the melting curve.
- Analysis of temperature dependence (T⁴) of sound velocity.
- Extraction of elastic stiffness constants and Grüneisen constants.
Main Results:
- Sound velocity changes were proportional to T⁴ for all modes and orientations.
- Six independent elastic stiffness constants of the nuclear-spin part were determined.
- Grüneisen constants for compressional strain exceeded those for shear strain.
Conclusions:
- The T⁴ dependence of sound velocity is attributed to nuclear spin energy.
- The multiple-spin-exchange model explains the observed anisotropy in Grüneisen constants.
- Tetragonal symmetry plays a key role in the spin wave behavior.