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Kondo-Induced Giant Isotropic Negative Thermal Expansion
D G Mazzone1,2, M Dzero3, Am M Abeykoon1
1National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA.
Physical Review Letters
|April 14, 2020
Summary
Researchers discovered a new way to control negative thermal expansion in Y-doped SmS. This unusual property, driven by a Kondo lattice state, shows potential for advanced material applications.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid State Chemistry
Background:
- Negative thermal expansion (NTE) is a rare phenomenon with significant technological potential.
- Understanding the mechanisms behind NTE is crucial for material design and application.
- Samarium sulfide (SmS) exhibits intriguing electronic and volume phase transitions.
Purpose of the Study:
- To investigate the 4f-electronic properties of Y-doped SmS using advanced spectroscopic and diffraction techniques.
- To elucidate the relationship between electronic structure and negative thermal expansion in this material.
- To explore the influence of Yttrium (Y) doping and chemical disorder on NTE properties.
Main Methods:
- X-ray spectroscopy and diffraction were employed to probe the electronic and structural characteristics.
- The Kondo volume collapse model was utilized for theoretical interpretation of experimental results.
- Systematic variation of Yttrium concentration allowed for tuning of material properties.
Main Results:
- An unprecedented decrease in bulk Samarium (Sm) valence exceeding 20% was observed at low temperatures.
- A strong coupling between an emergent Kondo lattice state and significant isotropic volume change was identified as the cause.
- The magnitude and temperature range of NTE were found to be tunable based on Y concentration and chemical disorder.
Conclusions:
- Y-doped SmS exhibits tunable, giant, and isotropic negative thermal expansion.
- The findings highlight the role of the Kondo lattice state in driving NTE.
- This research opens new pathways for designing advanced materials with controlled NTE for diverse applications.
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