Related Experiment Video
Updated: Oct 12, 2025
09:06
Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
8.3K
Spin fluctuations yield zT enhancement in ferromagnets
Md Mobarak Hossain Polash1,2, Daryoosh Vashaee1,2
1Department of Materials Science and Engineering, NC State University, Raleigh, NC 27606, USA.
Iscience
|November 25, 2021
Summary
Spin fluctuations (SF) significantly enhance thermoelectric performance. This study reports an 80% increase in the thermoelectric figure-of-merit (zT) in ferromagnetic CrTe due to SF, a crucial finding for advanced thermoelectric materials.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Thermoelectrics
Background:
- Thermoelectric materials convert heat to electricity.
- Spin fluctuations (SF) are known to influence thermopower.
- Enhancement of the thermoelectric figure-of-merit (zT) by SF remained unproven.
Purpose of the Study:
- To demonstrate and quantify the enhancement of zT by SF in a ferromagnetic material.
- To investigate the impact of SF on electron and phonon transport.
- To provide a fundamental understanding for designing spin-driven thermoelectrics.
Main Methods:
- Experimental synthesis and characterization of ferromagnetic CrTe.
- Measurement of field-dependent thermoelectric transport properties (thermopower, thermal conductivity).
- Analysis using theoretical models to explain observed phenomena.
Main Results:
- Nearly 80% enhancement in zT observed in CrTe near 335 K due to SF.
- External magnetic fields suppressed thermopower enhancement and increased thermal conductivity, confirming SF's role.
- Experimental data showed good agreement with theoretical models.
Conclusions:
- Spin fluctuations are crucial for significantly enhancing thermoelectric figure-of-merit (zT).
- Ferromagnetic CrTe exhibits substantial zT enhancement driven by SF.
- This work paves the way for developing high-performance spin-driven thermoelectric devices.
More Related Videos
Related Concept Videos
01:31Ferromagnetism
2.5K
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
2.5K
01:23Atomic Nuclei: Nuclear Relaxation Processes
763
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.
763
01:26Diamagnetism
2.5K
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
2.5K
01:05Atomic Nuclei: Magnetic Resonance
808
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
808
01:03Atomic Nuclei: Nuclear Spin State Overview
1.2K
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of...
1.2K
03:02Colors and Magnetism
12.5K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
12.5K