Related Experiment Video
Updated: Jul 11, 2025
11:21
Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
7.5K
Critical slowing down near a magnetic quantum phase transition with fermionic breakdown
Chia-Jung Yang1, Kristin Kliemt2, Cornelius Krellner2
1Department of Materials, ETH Zurich, Zurich, Switzerland.
Nature Physics
|November 16, 2023
Summary
Researchers observed critical slowing down in fermionic excitations for the first time in YbRh2Si2, near a quantum phase transition. This finding challenges previous assumptions about fermionic behavior during phase transitions.
Area of Science:
- Condensed Matter Physics
- Quantum Materials
- Spectroscopy
Background:
- Critical slowing down is a universal phenomenon near continuous phase transitions, typically observed in bosonic excitations.
- Fermionic excitations are not generally expected to exhibit critical slowing down due to their distinct quantum mechanical properties.
Purpose of the Study:
- To investigate the dynamics of fermionic excitations near a quantum phase transition.
- To explore the phenomenon of critical slowing down in fermionic systems, specifically in YbRh2Si2.
Main Methods:
- Terahertz time-domain spectroscopy was employed to probe the electronic dynamics.
- Analysis of heavy-fermion spectral weight and quasiparticle excitation rates as a function of temperature.
Main Results:
- Evidence for critical slowing down was found in fermionic excitations of YbRh2Si2 near a quantum phase transition.
- Observed temperature-dependent behavior of heavy-fermion spectral weight and quasiparticle excitation rates.
- The results indicate a breakdown of heavy fermions near the quantum phase transition.
Conclusions:
- The study provides the first experimental evidence of fermionic critical slowing down.
- This phenomenon is linked to heavy-fermion breakdown near quantum phase transitions.
- The findings may help classify a broader range of unexplored fermionic quantum phase transitions.
More Related Videos
Related Concept Videos
01:23Atomic Nuclei: Nuclear Relaxation Processes
657
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
657
01:14Atomic Nuclei: Nuclear Spin State Population Distribution
987
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
987
02:31Phase Transitions
19.1K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
19.1K
01:12Fermi Level Dynamics
257
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
257
02:39Phase Transitions: Melting and Freezing
12.4K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
12.4K
01:23Magnetic Field due to Moving Charges
8.7K
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...
8.7K