Critical Behaviour of Heisenberg Ferromagnets with Dipolar Interactions and Uniaxial Anisotropy

2005 ◽  
pp. 9-29
Author(s):  
S.N. Kaul
Keyword(s):  
Uniaxial Anisotropy ◽  
Critical Behaviour ◽  
Dipolar Interactions

D-STRAIN, g-STRAIN, AND DIPOLAR INTERACTIONS IN THE Fe8 AND Mn12 SINGLE MOLECULE MAGNETS: AN EPR LINESHAPE ANALYSIS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3326-3329 ◽  
Author(s):  
S. HILL ◽  
S. MACCAGNANO ◽  
R. ACHEY ◽  
N. DALAL ◽  
K. PARK
Keyword(s):  
Single Molecule ◽  
High Field ◽  
Anisotropy Parameter ◽  
Uniaxial Anisotropy ◽  
High Sensitivity ◽  
Dipolar Interactions ◽  
Single Molecule Magnets ◽  
Field Frequency ◽  
Lineshape Analysis ◽  
Oriented Single Crystal

We report high sensitivity, high field/frequency (up to 9 tesla/210 GHz) EPR measurements on the Fe8 and Mn12 single molecule magnets. Oriented single crystal studies, carried out in well defined experimental geometries, enable very accurate determinations of EPR lineshapes; we note that this is not possible when studying aligned powders or polycrystals. Analysis of individual resonances, which we can assign to known transitions, reveal complex nonlinearities in the linewidths as functions of energy eigenstate, frequency, and temperature. Our findings compare favorably with recent calculations which introduce distributions in the uniaxial anisotropy parameter D, the Landé g-factor, and dipolar interactions.

Phase transitions in ferromagnets with dipolar interactions and uniaxial anisotropy

1995 ◽  
Vol 51 (21) ◽  
pp. 15229-15249 ◽  
Author(s):  
K. Ried ◽  
Y. Millev ◽  
M. Fähnle ◽  
H. Kronmüller
Keyword(s):  
Phase Transitions ◽  
Uniaxial Anisotropy ◽  
Dipolar Interactions

Monte Carlo Simulation of Thin Magnetic Films Critical Behavior

2016 ◽  
Vol 845 ◽  
pp. 89-92
Author(s):  
Pavel V. Prudnikov ◽  
Anna P. Soldusova ◽  
Maria A. Medvedeva ◽  
Natalia I. Piskunova
Keyword(s):  
Monte Carlo ◽  
Critical Behavior ◽  
Uniaxial Anisotropy ◽  
Critical Time ◽  
Monte Carlo Study ◽  
Magnetic Films ◽  
Dipolar Interaction ◽  
Dipolar Interactions ◽  
Thin Magnetic Films ◽  
System Properties

The Monte-Carlo study deals with ultrathin magnetic films critical behavior. Uniaxial anisotropy, long-range dipolar interactions and external magnetic field competition effects on phase transition, domain structure and system properties were investigated. Striped spin configurations are demonstrated for system with strong dipolar interaction. The effective antiferromagnetic character of dipolar interaction is observed in bilayer structure. Memory effects in non-equilibrium critical time relaxation of magnetization and autocorrelation function are investigated.

scholarly journals Tuning Easy Magnetization Direction and Magnetostatic Interactions in High Aspect Ratio Nanowires

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3042
Author(s):  
Hafsa Khurshid ◽  
Rahana Yoosuf ◽  
Bashar Afif Issa ◽  
Atta G. Attaelmanan ◽  
George Hadjipanayis
Keyword(s):  
Magnetic Properties ◽  
Uniaxial Anisotropy ◽  
Growth Direction ◽  
Diameter Ratio ◽  
Nanowire Growth ◽  
Dipolar Interactions ◽  
Easy Magnetization ◽  
Magnetization Direction ◽  
Cobalt Nanowires ◽  
Easy Magnetization Direction

Cobalt nanowires have been synthesized by electrochemical deposition using track-etched anodized aluminum oxide (AAO) templates. Nanowires with varying spacing-to-diameter ratios were prepared, and their magnetic properties were investigated. It is found that the nanowires’ easy magnetization direction switches from parallel to perpendicular to the nanowire growth direction when the nanowire’s spacing-to-diameter ratio is reduced below 0.7, or when the nanowires’ packing density is increased above 5%. Upon further reduction in the spacing-to-diameter ratio, nanowires’ magnetic properties exhibit an isotropic behavior. Apart from shape anisotropy, strong dipolar interactions among nanowires facilitate additional uniaxial anisotropy, favoring an easy magnetization direction perpendicular to their growth direction. The magnetic interactions among the nanowires were studied using the standard method of remanence curves. The demagnetization curves and Delta m (Δm) plots showed that the nanowires interact via dipolar interactions that act as an additional uniaxial anisotropy favoring an easy magnetization direction perpendicular to the nanowire growth direction. The broadening of the dipolar component of Δm plots indicate an increase in the switching field distribution with the increase in the nanowires’ diameter. Our findings provide an important insight into the magnetic behavior of cobalt nanowires, meaning that it is crucial to design them according to the specific requirements for the application purposes.

Grain separation enhanced magnetic coercivity in Pt/Co multilayers.

1993 ◽  
Vol 51 ◽  
pp. 1038-1039 ◽  
Author(s):  
G.A. Bertero ◽  
R. Sinclair
Keyword(s):  
Remanent Magnetization ◽  
Strong Influence ◽  
Uniaxial Anisotropy ◽  
Magnetic Coupling ◽  
Recording Media ◽  
Magnetic Media ◽  
Signal To Noise ◽  
Out Of Plane ◽  
Longitudinal Recording ◽  
The Relationship

Pt/Co multilayers displaying perpendicular (out-of-plane) magnetic anisotropy and 100% perpendicular remanent magnetization are strong candidates as magnetic media for the next generation of magneto-optic recording devices. The magnetic coercivity, Hc, and uniaxial anisotropy energy, Ku, are two important materials parameters, among others, in the quest to achieving higher recording densities with acceptable signal to noise ratios (SNR). The relationship between Ku and Hc in these films is not a simple one since features such as grain boundaries, for example, can have a strong influence on Hc but affect Ku only in a secondary manner. In this regard grain boundary separation provides a way to minimize the grain-to-grain magnetic coupling which is known to result in larger coercivities and improved SNR as has been discussed extensively in the literature for conventional longitudinal recording media.We present here results from the deposition of two Pt/Co/Tb multilayers (A and B) which show significant differences in their coercive fields.

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