Related Experiment Video
Updated: Jul 28, 2026
11:07
Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties
Published on: August 15, 2015
Thermal Hall Effect in a Phonon-Glass Ba_{3}CuSb_{2}O_{9}
K Sugii1, M Shimozawa1, D Watanabe1
1The Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
Physical Review Letters
|April 22, 2017
Summary
Researchers observed a unique thermal Hall signal in the quantum spin liquid candidate, Ba3CuSb2O9. This signal, linked to phonon scattering by copper spins, suggests a phonon Hall effect in this material.
Area of Science:
- Condensed Matter Physics
- Quantum Materials
- Magnetism
Background:
- Quantum spin liquids are exotic states of matter with potential applications in quantum computing.
- Understanding thermal transport properties is crucial for identifying and characterizing quantum spin liquid candidates.
- Barium copper antimonate (Ba3CuSb2O9) is a promising material exhibiting properties suggestive of a quantum spin liquid state.
Purpose of the Study:
- To investigate the thermal transport properties of Ba3CuSb2O9, specifically focusing on the thermal Hall effect.
- To explore the relationship between thermal conductivity, spin dynamics, and the emergence of a spin gap.
- To elucidate the underlying mechanism responsible for the observed thermal Hall signal in this quantum spin liquid candidate.
Main Methods:
- Measurement of longitudinal and transverse thermal conductivity as a function of temperature.
- Analysis of the temperature dependence of thermal conductivity, particularly below the spin gap opening temperature (50 K).
- Theoretical modeling to interpret the thermal Hall signal in the context of phonon-spin interactions.
Main Results:
- A distinct thermal Hall signal was observed in Ba3CuSb2O9.
- The transverse thermal conductivity exhibited a power-law temperature dependence below 50 K, coinciding with the opening of a spin gap.
- The longitudinal thermal conductivity was found to be very low.
Conclusions:
- The observed thermal Hall signal is attributed to a phonon Hall effect.
- This effect is likely induced by strong phonon scattering from randomly oriented Cu2+ spins within the material's structure.
- The findings provide further evidence for Ba3CuSb2O9 as a quantum spin liquid candidate and highlight the role of spin-phonon interactions in its thermal properties.
Related Concept Videos
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
01:25Heat Capacities of an Ideal Gas III
The number of independent ways a gas molecule can move along straight line, rotate, and vibrate is called its degrees of freedom. Supposing d represents the number of degrees of freedom of an ideal gas, the molar heat capacity at constant volume of an ideal gas in terms of d is
01:30The Hall Effect
Edwin H. Hall, in the year 1879, devised an experiment that could be used to identify the polarity of the predominant charge carriers in a conducting material. From a historical perspective, this experiment was the first to demonstrate that the charge carriers in most metals are negative.
01:17Theory of Metallic Conduction
The conduction of free electrons inside a conductor is best described by quantum mechanics. However, a classical model makes predictions close to the results of quantum mechanics. It is called the theory of metallic conduction.
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
01:28Standing Waves in a Cavity
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by:
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...