Néel relaxation
E326459
Néel relaxation is a magnetic relaxation process in which the magnetization of single-domain nanoparticles flips between energy minima due to thermal fluctuations without physical rotation of the particles.
All labels observed (1)
| Label | Occurrences |
|---|---|
| Néel relaxation canonical | 3 |
Statements (43)
| Predicate | Object |
|---|---|
| instanceOf |
magnetic relaxation process
ⓘ
superparamagnetic relaxation mechanism ⓘ |
| anisotropyEffect | relaxation time increases with increasing anisotropy constant ⓘ |
| assumes | single-domain magnetic state of the particle ⓘ |
| characteristicFeature |
does not require physical rotation of the particle
ⓘ
magnetization flips between energy minima ⓘ |
| competesWith | Brownian relaxation ⓘ |
| dependsOn |
magnetic anisotropy constant
ⓘ
magnetic anisotropy energy barrier ⓘ particle volume ⓘ temperature ⓘ |
| dominatesWhen |
magnetic anisotropy energy barrier is moderate
ⓘ
particles are immobilized in a solid matrix ⓘ |
| drivenBy | thermal fluctuations ⓘ |
| fieldOfStudy |
condensed matter physics
ⓘ
materials science ⓘ nanomagnetism ⓘ |
| hasEquation | τ_N = τ_0 · exp(KV / k_B T) ⓘ |
| hasParameter |
K (anisotropy constant)
ⓘ
T (absolute temperature) ⓘ V (particle volume) ⓘ k_B ⓘ
surface form:
k_B (Boltzmann constant)
τ_0 (attempt time) ⓘ τ_N (Néel relaxation time) ⓘ |
| historicalPeriod | mid-20th century theoretical development ⓘ |
| leadsTo |
frequency-dependent AC magnetic susceptibility
ⓘ
time-dependent decay of magnetization ⓘ |
| magnetizationChange | occurs via coherent or quasi-coherent spin rotation ⓘ |
| mechanism | thermally activated magnetization reversal ⓘ |
| namedAfter | Louis Néel ⓘ |
| occursIn |
single-domain magnetic nanoparticles
ⓘ
superparamagnetic particles ⓘ |
| relatedConcept |
Arrhenius equation
ⓘ
surface form:
Arrhenius law
energy barrier crossing ⓘ |
| relevantTo |
magnetic data storage stability
ⓘ
magnetic hyperthermia ⓘ magnetic nanoparticle imaging ⓘ superparamagnetism ⓘ |
| sizeEffect | relaxation time decreases with decreasing particle volume ⓘ |
| suppressedWhen | temperature is very low compared to anisotropy energy barrier ⓘ |
| temperatureEffect | relaxation time decreases with increasing temperature ⓘ |
| timeScale | typically between 10^-12 s and many seconds depending on parameters ⓘ |
| usedIn | analysis of blocking temperature in superparamagnets ⓘ |
Referenced by (3)
Full triples — surface form annotated when it differs from this entity's canonical label.