Related Experiment Video
Updated: Aug 5, 2026
10:40
High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
Pseudochiral Phonons from Octupolar Magnetic Order
Ruairidh Sutcliffe1, Kathleen Hart1, Swati Chaudhary2
1University of Toronto, Department of Physics, 60 St. George Street, Toronto, Ontario, M5S 1A7 Canada.
Physical Review Letters
|July 31, 2026
Summary
We introduce pseudochiral phonons in multipolar magnets, distinct from chiral phonons. These novel phonons, detected via Raman spectroscopy, can reveal hidden octupolar order in quantum materials.
Area of Science:
- Condensed Matter Physics
- Quantum Materials Science
- Phononics
Background:
- Chiral phonons exhibit large magnetic responses in dipolar magnets.
- Multipolar magnets possess complex magnetic orders beyond simple dipoles.
Purpose of the Study:
- Introduce and define pseudochiral phonons emerging in multipolar magnets.
- Investigate the relationship between multipolar order and phonon degeneracy breaking.
- Propose a spectroscopic method to detect hidden octupolar order.
Main Methods:
- Theoretical modeling of Raman active phonons (E_g doublets) coupled to quadrupolar moments.
- Path integral approach to compute temperature-dependent phonon Green's function.
- Monte Carlo simulations to sample thermal background and pseudospin fluctuations.
Main Results:
- Distinct multipolar orders break phonon degeneracy differently: quadrupolar orders favor nonchiral modes, octupolar orders favor pseudochiral phonons.
- Pseudochiral phonons exhibit unconventional properties linked to time-reversal breaking octupolar order.
- The phonon matrix Green's function captures the dynamic interactions.
Conclusions:
- Pseudochiral phonons are a new class of quasiparticles in multipolar magnets.
- Helicity-resolved Raman spectroscopy can probe hidden octupolar order.
- This work opens avenues for exploring novel quantum phenomena in materials like Ba_2CaOsO_6 and PrV_2Al_20.
Related Concept Videos
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
01:25Magnetic Field due to Moving Charges
A stationary charge creates and interacts with the electric field, while a moving charge creates a magnetic field.
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...
01:29Potential Due to a Polarized Object
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
01:15Magnetic Vector Potential
In electrostatics, the electric field can be written as the negative gradient of the potential. In magnetostatics, the zero divergence of the magnetic field ensures that the magnetic field can be expressed as the curl of a vector potential. This potential is known as the magnetic vector potential.
Consider an ideal solenoid with n turns per unit length and radius R. If I is the current through the solenoid, the magnetic field inside the solenoid is expressed as the product of vacuum...
Consider an ideal solenoid with n turns per unit length and radius R. If I is the current through the solenoid, the magnetic field inside the solenoid is expressed as the product of vacuum...
02:54Molecular and Ionic Solids
Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their interparticle interactions.
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...