Pressure effect on magnetic hysteresis parameters of single-domain magnetite contained in natural plagioclase crystal

Abstract Presently a wide spread of research activities is pursued in the area of theoretical, computational and experimental aspects of vibration studies in laminated composite structures with embedded or surface bonded smart layers in order to improve the performance of components in aerospace, mechanical, robotics, and electronic equipments. The key to the successful fabrication of these components with improved properties is the development of smart materials by materials engineering and understanding the fundamentals of materials science. It is in this context that we have developed a novel smart thin film processing method based upon pulsed laser deposition to process nanocrystalline materials with accurate size and interface control with improved mechanical and magnetic properties. Using this method, single domain nanocrystalline Fe and Ni particles in 5–10 nm size range embedded in amorphous as well as crystalline alumina have been produced. By controlling the size distribution in confined layers, it was possible to tune the magnetic properties from superparamagnetic to ferromagnetic in a controlled way. Magnetization measurements of these thin film composites as function of field and temperature were carried out using a superconducting quantum interference device (SQUID) magnetometer. Magnetic hysteresis characteristics below the blocking temperature are consistent with single-domain behavior. Mechanical properties were measured using nano-indentation measurements. The hardness of the Fe and Ni-Al2O3 nanocomposites was found to vary strongly with the size do Fe and Ni nanodots in the alumina matrix. For example, the hardness of Fe-Al2O3 system increased from 15 GPa to 28 GPa when the size of Fe dots in alumina was increased from 5 nm to 9 nm. It is envisioned that this types of smart films can be used in magnetic recording, ferrofluid technology, magnetocaloric refrigeration, biomedicine, biotechnology, aerospace applications where hard and wear-resistant coatings are also very important for its survival.

Download Full-text

Magnetic hysteresis as a function of low temperature in rocks: evidence for internal stress control of remanence in multi-domain and pseudo-single-domain magnetite

Physics of The Earth and Planetary Interiors ◽

10.1016/0031-9201(90)90003-g ◽

1990 ◽

Vol 64 (1) ◽

pp. 21-36 ◽

Cited By ~ 23

Author(s):

J.P. Hodych

Keyword(s):

Low Temperature ◽

Internal Stress ◽

Magnetic Hysteresis ◽

Single Domain ◽

Stress Control

Download Full-text

Dynamic magnetic hysteresis in single-domain particles with uniaxial anisotropy

Physical Review B ◽

10.1103/physrevb.82.174423 ◽

2010 ◽

Vol 82 (17) ◽

Cited By ~ 62

Author(s):

I. S. Poperechny ◽

Yu. L. Raikher ◽

V. I. Stepanov

Keyword(s):

Magnetic Hysteresis ◽

Uniaxial Anisotropy ◽

Single Domain

Download Full-text

Designing magnetic superlattices that are composed of single domain nanomagnets

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.5.109 ◽

2014 ◽

Vol 5 ◽

pp. 956-963 ◽

Cited By ~ 1

Author(s):

Derek M Forrester ◽

Feodor V Kusmartsev ◽

Endre Kovács

Keyword(s):

Phase Diagrams ◽

Coupling Strength ◽

Magnetic Moments ◽

Magnetic Hysteresis ◽

Single Domain ◽

Magnetic Interactions ◽

Dynamical Analysis ◽

Complex Nature ◽

Phase Boundaries ◽

Average Magnetization

Background: The complex nature of the magnetic interactions between any number of nanosized elements of a magnetic superlattice can be described by the generic behavior that is presented here. The hysteresis characteristics of interacting elliptical nanomagnets are described by a quasi-static method that identifies the critical boundaries between magnetic phases. A full dynamical analysis is conducted in complement to this and the deviations from the quasi-static analysis are highlighted. Each phase is defined by the configuration of the magnetic moments of the chain of single domain nanomagnets and correspondingly the existence of parallel, anti-parallel and canting average magnetization states. Results: We give examples of the phase diagrams in terms of anisotropy and coupling strength for two, three and four magnetic layers. Each phase diagrams character is defined by the shape of the magnetic hysteresis profile for a system in an applied magnetic field. We present the analytical solutions that enable one to define the “phase” boundaries between the emergence of spin-flop, anti-parallel and parallel configurations. The shape of the hysteresis profile is a function of the coupling strength between the nanomagnets and examples are given of how it dictates a systems magnetic response. Many different paths between metastable states can exist and this can lead to instabilities and fluctuations in the magnetization. Conclusion: With these phase diagrams one can find the most stable magnetic configurations against perturbations so as to create magnetic devices. On the other hand, one may require a magnetic system that can easily be switched between phases, and so one can use the information herein to design superlattices of the required shape and character by choosing parameters close to the phase boundaries. This work will be useful when designing future spintronic devices, especially those manipulating the properties of CoFeB compounds.

Download Full-text

Damping dependence in dynamic magnetic hysteresis of single-domain ferromagnetic particles

Physical Review B ◽

10.1103/physrevb.85.094425 ◽

2012 ◽

Vol 85 (9) ◽

Cited By ~ 14

Author(s):

H. El Mrabti ◽

P. M. Déjardin ◽

S. V. Titov ◽

Yu. P. Kalmykov

Keyword(s):

Magnetic Hysteresis ◽

Single Domain ◽

Ferromagnetic Particles

Download Full-text

Processing and Properties of Nanostructured Magnetic Materials

Materials: Processing, Characterization and Modeling of Novel Nano-Engineered and Surface Engineered Materials ◽

10.1115/imece2002-39364 ◽

2002 ◽

Author(s):

D. Kumar ◽

S. Yarmolenko ◽

J. Sankar ◽

J. Narayan ◽

A. Tiwari ◽

...

Keyword(s):

Magnetic Properties ◽

Magnetic Hysteresis ◽

Single Domain ◽

Dead Layer ◽

Blocking Temperature ◽

Ferromagnetic Behavior ◽

Ni Nanoparticles ◽

Interface Control ◽

Individual Grains ◽

Oxygen Bond

We report here a novel thin film processing method based upon pulsed laser deposition to process nanocrystalline materials with accurate size and interface control with improved mechanical and magnetic properties. Using this method, single domain nanocrystalline Fe and Ni particles in 5–10 nm size range embedded in amorphous alumina as well as crystalline TiN have been produced. By controlling the size distribution in confined layers, it was possible to tune the magnetic properties from superparamagnetic to ferromagnetic behavior. Magnetic hysteresis characteristics below the blocking temperature are consistent with single-domain behavior. The paper also presents our results from investigations in which scanning transmission electron microscopy with atomic number contrast (STEM-Z) and energy loss spectroscopy (EELS) were used to understand the atomic structure of Ni nanoparticles and interface between the nanoparticles and the surrounding matrices. It was interesting to learn from EELS measurements at interfaces of individual grains that Ni in alumina matrix does not from an ionic bond indicating the absence of metal-oxygen bond at the interface. The absence of metal-oxygen bond, in turn, suggests the absence of any dead layer on Ni nanoparticles even in an oxide matrix.

Download Full-text