Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Atomic Nuclei: Nuclear Relaxation Processes

Atomic 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...

Atomic Nuclei: Magnetic Resonance

Atomic Nuclei: Magnetic Resonance

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...

Atomic Nuclei: Nuclear Magnetic Moment

Atomic Nuclei: Nuclear Magnetic Moment

All atomic nuclei are positively charged. When they have a nonzero spin, they behave like rotating charges. As a consequence of their charge and spin, these nuclei generate a magnetic field (B). This, in turn, gives rise to a magnetic moment (μ), which is randomly oriented in the absence of an external magnetic field. When an external magnetic field (B0) is applied, the magnetic moment vectors can align with the field or against it in 2 + 1 orientations. A hydrogen nucleus, which is just a...

Atomic Nuclei: Nuclear Spin State Overview

Atomic Nuclei: Nuclear Spin State Overview

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 one, the...

Magnetic Fields

Magnetic Fields

A moving charge or a current creates a magnetic field in the surrounding space, in addition to its electric field. The magnetic field exerts a force on any other moving charge or current that is present in the field. Like an electric field, the magnetic field is also a vector field. At any position, the direction of the magnetic field is defined as the direction in which the north pole of a compass needle points.
A magnetic field is defined by the force that a charged particle experiences...

Potential Due to a Magnetized Object

Potential Due to a Magnetized Object

Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Solvothermal vapor annealing and environmental control setup with adjustable magnetic field module for grazing incidence small-angle x-ray scattering studies.

The Review of scientific instruments·2026

Same author

A new reference for changes in X-ray scattering from water due to temperature changes at ambient conditions.

Journal of synchrotron radiation·2026

Same author

Sub-Kelvin Resolution X-ray Diffraction Thermometry Defies the Existence of Nanoscale Hotspots in Induction Heated Magnetic Nanoparticles.

ACS nano·2026

Same author

Transport of green rust and biochar mixtures in porous media for in-situ remediation of chlorinated ethylenes.

Journal of contaminant hydrology·2025

Same author

Retrofittable plug-flow reactor for in situ high-temperature vibrating sample magnetometry with well-controlled gas atmospheres.

The Review of scientific instruments·2023

Same author

Universal Synthesis of Half-Metallic Diatomic Catalysts for Efficient Oxygen Reduction Electrocatalysis.

Small (Weinheim an der Bergstrasse, Germany)·2023

Search research articles

Related Experiment Video

Updated: May 28, 2026

Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains

Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains

Published on: July 20, 2022

Uniform excitations in magnetic nanoparticles.

Steen Mørup¹, Cathrine Frandsen, Mikkel Fougt Hansen

¹Department of Physics, Building 307, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.

Beilstein Journal of Nanotechnology

|October 7, 2011

Summary

Magnetic nanoparticles below blocking temperature exhibit uniform excitations, causing linear temperature dependence for magnetization and hyperfine fields, unlike bulk materials. This behavior is studied using Mössbauer spectroscopy and inelastic neutron scattering.

Keywords:

Mössbauer spectroscopy collective magnetic excitations neutron scattering spin waves superparamagnetic relaxation

More Related Videos

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

Published on: May 7, 2017

Related Experiment Videos

Last Updated: May 28, 2026

Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains

Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains

Published on: July 20, 2022

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

Published on: May 7, 2017

Area of Science:

Condensed Matter Physics
Materials Science
Nanotechnology

Background:

Superparamagnetic nanoparticles exhibit unique magnetic dynamics below their blocking temperature.
Bulk magnetic materials follow the Bloch T(3/2) law for temperature dependence.

Purpose of the Study:

To review magnetic excitations in nanoparticles below the superparamagnetic blocking temperature.
To contrast nanoparticle magnetic behavior with bulk materials.

Main Methods:

Mössbauer spectroscopy to study temperature dependence of average magnetization.
Inelastic neutron scattering to investigate the energy of uniform excitations.

Main Results:

Magnetic dynamics in nanoparticles below blocking temperature are dominated by uniform excitations.
A linear temperature dependence of magnetization and magnetic hyperfine field is observed.
This contrasts with the Bloch T(3/2) law typically seen in bulk magnetic materials.

Conclusions:

Uniform excitations are key to understanding nanoparticle magnetism below blocking temperature.
Mössbauer spectroscopy and inelastic neutron scattering are effective tools for studying these phenomena.