Related Experiment Video
Updated: Jun 5, 2026
07:42
Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains
Published on: July 20, 2022
Unconventional magnetization processes and thermal runaway in spin-ice Dy2Ti2O7
D Slobinsky1, C Castelnovo, R A Borzi
1SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, United Kingdom.
Physical Review Letters
|January 15, 2011
Summary
Investigating spin ice Dy2Ti2O7 revealed that below its freezing temperature, magnetization curves deviate from equilibrium. Field-driven monopole excitations cause energy barriers, leading to magnetization steps and sample heating.
Area of Science:
- Condensed Matter Physics
- Magnetism
- Thermodynamics
Background:
- Spin ice materials like Dy2Ti2O7 exhibit complex magnetic behaviors.
- Understanding nonequilibrium dynamics is crucial for characterizing exotic magnetic states.
Purpose of the Study:
- To investigate the nonequilibrium magnetization dynamics of Dy2Ti2O7.
- To correlate magnetization behavior with temperature changes under varying field sweep rates.
Main Methods:
- Magnetization measurements as a function of magnetic field sweep rate.
- Temperature measurements of the sample during magnetization.
Main Results:
- Below the freezing temperature (T(equil)≈600 mK), equilibrium magnetization is not achieved even at slow sweep rates.
- Magnetization curves show flatter initial behavior and sharp steps at higher sweep rates.
- Sharp temperature peaks accompany magnetization steps, indicating inefficient heat dissipation.
Conclusions:
- Nonequilibrium magnetization is governed by energy barriers related to spin flips on filaments.
- Field-driven magnetic monopole excitations dictate the magnetization process.
- Sample heating due to released Zeeman energy can trigger chain reactions.
Related Concept Videos
01:30Paramagnetism
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
01:26Diamagnetism
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.
01:14Atomic Nuclei: Nuclear Spin State Population Distribution
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.
01:28Types Of Superconductors
A superconductor is a substance that offers zero resistance to the electric current when it drops below a critical temperature. Zero resistance is not the only interesting phenomenon as materials reach their transition temperatures. A second effect is the exclusion of magnetic fields. This is known as the Meissner effect. A light, permanent magnet placed over a superconducting sample will levitate in a stable position above the superconductor. High-speed trains that levitate on strong...
01:23Atomic Nuclei: Nuclear Relaxation Processes
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. This...
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...