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Updated: May 15, 2025
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High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
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Thermodynamic signatures of diagonal nematicity in RbFe2As2 superconductor
Yuta Mizukami1,2, Ohei Tanaka1, Kousuke Ishida1
1Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan.
PNAS Nexus
|April 7, 2025
Summary
This study provides thermodynamic evidence for diagonal nematicity in iron-based superconductors using heat capacity measurements. The findings suggest a charge-driven mechanism for this unique electronic nematic state.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Superconductivity
Background:
- Electronic nematic states break rotational symmetry in correlated materials.
- Iron-based superconductors typically exhibit nematicity aligned with the Fe-Fe lattice direction.
- A unique diagonal nematicity along the Fe-As direction has been proposed for heavily hole-doped ( or Cs).
Purpose of the Study:
- To investigate the presence and orientation of nematic fluctuations in using thermodynamic measurements.
- To clarify conflicting outcomes from previous transport studies on diagonal nematicity.
- To elucidate the mechanism and thermodynamic properties of the diagonal nematic transition.
Main Methods:
- High-resolution heat capacity measurements with in-plane magnetic field rotation.
- Analysis of field-angle dependence of specific heat near the superconducting transition.
- Mössbauer spectroscopy to probe the nematic transition and magnetic ordering.
Main Results:
- No anomaly in specific heat's temperature dependence indicated a nematic transition.
- Field-angle dependence revealed clear 2-fold oscillations, providing thermodynamic evidence for diagonal nematicity.
- Mössbauer spectroscopy detected the nematic transition at K without static magnetism.
Conclusions:
- Diagonal nematicity in is thermodynamically confirmed.
- The nematicity likely arises from charge degrees of freedom, not static magnetism.
- This suggests an unusual mechanism for the nematic transition in this material.
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