Magnetic hysteresis of a rectangular lattice of interacting single‐domain ferromagnetic spheres

1992 ◽  
Vol 72 (12) ◽  
pp. 5792-5798 ◽  
Author(s):  
John Lam
Keyword(s):  
Magnetic Hysteresis ◽  
Single Domain ◽  
Rectangular Lattice

Tunable Magnetic and Mechanical Properties in Metal Ceramic Composite Thin Films

2001 ◽  
Author(s):  
D. Kumar ◽  
J. Sankar ◽  
J. Narayan ◽  
A. Kvit
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Magnetic Properties ◽  
Smart Materials ◽  
Quantum Interference ◽  
Composite Structures ◽  
Magnetic Hysteresis ◽  
Single Domain ◽  
Blocking Temperature ◽  
Research Activities

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.

Dynamic magnetic hysteresis in single-domain particles with uniaxial anisotropy

2010 ◽  
Vol 82 (17) ◽  
Author(s):  
I. S. Poperechny ◽  
Yu. L. Raikher ◽  
V. I. Stepanov
Keyword(s):  
Magnetic Hysteresis ◽  
Uniaxial Anisotropy ◽  
Single Domain

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

2015 ◽  
Vol 202 (1) ◽  
pp. 394-401 ◽  
Author(s):  
Masahiko Sato ◽  
Yuhji Yamamoto ◽  
Takashi Nishioka ◽  
Kazuto Kodama ◽  
Nobutatsu Mochizuki ◽  
...  
Keyword(s):  
Pressure Effect ◽  
Magnetic Hysteresis ◽  
Single Domain ◽  
Plagioclase Crystal

scholarly journals Designing magnetic superlattices that are composed of single domain nanomagnets

2014 ◽  
Vol 5 ◽  
pp. 956-963 ◽  
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.

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

2012 ◽  
Vol 85 (9) ◽  
Author(s):  
H. El Mrabti ◽  
P. M. Déjardin ◽  
S. V. Titov ◽  
Yu. P. Kalmykov
Keyword(s):  
Magnetic Hysteresis ◽  
Single Domain ◽  
Ferromagnetic Particles

Processing and Properties of Nanostructured Magnetic Materials

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.

Magnetic hysteresis of 0.6–110 μm magnetites across the Verwey transition

2019 ◽  
Vol 56 (9) ◽  
pp. 958-972 ◽  
Author(s):  
David J. Dunlop ◽  
Özden Özdemir ◽  
Song Xu
Keyword(s):  
Magnetic Hysteresis ◽  
Magnetic Domain ◽  
Hysteresis Loops ◽  
Single Domain ◽  
Magnetic Domains ◽  
Verwey Transition ◽  
Electron Microscopic ◽  
Structure Changes ◽  
Saturation Remanence ◽  
Major Domain

We report saturation magnetization, Ms, saturation remanence, Mrs, coercive force, Hc, and remanence coercivity, Hcr, as a function of grain size, d, and temperature, T, for 0.6–135 μm magnetites. Five annealed and four unannealed samples were measured at 5–10 K intervals from 300 to 20 K. Mrs and Hc increase by factors of 1.5–4 in cooling through the Verwey transition (TV ≈ 120 K) and by smaller amounts around 50 K. Hysteresis properties change continuously over ≈20 K below TV or for annealed 0.6, 3, and 6 μm grains, within ≈10 K below TV. Hc(d) changes for annealed magnetites from ∼d–0.5 at 300 K to ∼d–0.6–d–0.7 at 120–130 K to ∼d–0.3 at 80–100 K. Day plots of Mrs(T)/Ms(T) versus Hcr(T)/Hc(T) indicate major domain structure changes with T, e.g., 6 μm grains change from large pseudo-single-domain (PSD) at 300 K to multidomain (MD) just above TV and return to PSD below TV, evolving to higher Mrs and Hc down to 20 K. Hysteresis loops change from normal at 300 K to slightly constricted near TV to severely constricted below 50 K. We interpret these results in the light of electron microscopic observations by Kasama et al. (2010 , 2012) . Hardening of magnetic hysteresis below TV and the evolution from MD to PSD, and even to single-domain in the finest grains, results from subdivision of grains by monoclinic twinning, reduced magnetic domain sizes in monoclinic magnetite, and confinement of magnetic domains within twin domains. Constricted hysteresis loops indicate coexisting magnetically hard and soft phases, initially growing monoclinic regions and residual cubic magnetite.

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