A Dissipative Quantum Dynamic Approach to Magnetic Hysteresis Loop and Magnetization Relaxation for Molecule Magnet Mn12

2003 ◽  
Vol 17 (17) ◽  
pp. 3215-3224
Author(s):  
Yuanchang Su ◽  
Yongjin Jiang
Keyword(s):  
Hysteresis Loop ◽  
Time Evolution ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Hysteresis Loop ◽  
Quantum Dynamic ◽  
Magnetization Relaxation ◽  
Resonant Tunnelling ◽  
State Evolution ◽  
Different Temperatures

A new approach to the magnetic hysteresis loop and magnetization relaxation of molecule magnet, Mn12, is presented. The method, so called "quasi-thermal equilibrium (QTE) + erase phase (EP)" (QTE + EP), leads the dissipation in state evolution. The method gives an method to approach an irreversible quantum dynamic tunnelling and time evolution of system and straightly leads the hysteresis loops. The QTE can work well for the double-well system and is able to be extended to the multi-wells quantum system. The EP is based on the physics of random interaction with the environment that results the phase de-coherence or say "re-initial" of the phase of quantum state during the time evolution. The stairs in the magnetic loops of Mn12 we have obtained quantitatively show the quantum resonant tunnelling. The relaxation of magnetization from initial lowest state is calculated for different temperatures and well shows the exponential behavior. The theoretical results well agree with the experiments.

Exchange Bias Properties in Bulk Ni45Co5Mn38Sn12 Heusler Alloy

2014 ◽  
Vol 875-877 ◽  
pp. 272-276 ◽  
Author(s):  
Chao Jing ◽  
Ye Jun Yang ◽  
Dong Hua Yu ◽  
Zhe Li ◽  
Xiao Long Wang ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Exchange Bias ◽  
Heusler Alloy ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Bias Field ◽  
Magnetic Hysteresis Loop ◽  
Zero Field ◽  
Co Substitution ◽  
Exchange Bias Field

We report the exchange bias properties in the bulk Ni45Co5Mn38Sn12quaternary Heusler alloy. The ferromagnetic (FM) –antiferromagnetic (AFM) interactions get reinforced after the Co substitution for Ni in the Ni-Mn-Sn alloy, which increase the exchange bias field (HE). A maximum shift in hysteresis loops of 306 Oe was observed in the 10 kOe field cooled sample. The origin of this large exchange bias field has been discussed. Magnetic hysteresis loop obtained in the zero field cooled (ZFC) mode shows double-shifted loop, and the reason of this phenomenon has been explained in detail.

scholarly journals Observation of Negative Magnetic Hysteresis Loop in ZnO Thin Films

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Micah Haseman ◽  
Pooneh Saadatkia ◽  
David Winarski ◽  
Armando Hernandez ◽  
Matt Kusz ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Diluted Magnetic Semiconductors ◽  
Magnetic Semiconductors ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Magnetic Hysteresis Loop ◽  
Structural Defects ◽  
Zno Films ◽  
Doped Zno

We report on the observation of an unusual negative magnetic hysteresis loop in ZnO thin film codoped with cobalt and aluminum (Co-Al:ZnO), while other transition-metal-doped ZnO films, such as Cu-doped ZnO and Mn-doped ZnO, exhibit normal hysteresis loops. The unusual magnetic behavior is ascribed to the presence of double magnetic layers with different magnetic moments due to the change of structural defects across the film layers. Positron annihilation measurements confirmed the presence of unique microstructural changes in the Co-Al:ZnO film. This study shows that defects in diluted magnetic semiconductors may induce not only ferromagnetism but also novel magnetic behaviors.

MULTIFERROISM AND MAGNETOELECTRIC COUPLING IN NANO-MICROSCALE LEAD-FREE COMPOSITE BY 0.3Co-FERRITE AND 0.7(K0.5Na0.5)NbO3-BASED FERROELECTRIC MATRIX

2011 ◽  
Vol 25 (32) ◽  
pp. 4481-4488 ◽  
Author(s):  
YUN ZHOU ◽  
XINYAN WANG ◽  
LI LI ◽  
YULING SU ◽  
JINCANG ZHANG ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Dilution Effect ◽  
Magnetic Hysteresis Loop ◽  
Lead Free ◽  
Voltage Coefficient ◽  
Polarization Electric Field ◽  
Magnetic Hysteresis Loops ◽  
Potential Use

Nontoxic lead-free multiferroic composites are synthesized by incorporating the dispersed 0.3 CoFe 2 O 4 (CFO) ferromagnetic nanoparticles into 0.7( K 0.5 Na 0.5) NbO 3- LiSbO 3 (KNN-LS5.2) ferroelectric micromatrix. The multiferroicity of the composite can be verified by polarization-electric field hysteresis loop and magnetic hysteresis loop. The composite exhibits excellent magnetic properties. A dilution effect is observed in magnetic hysteresis loops. The field dependence of ME voltage coefficient is given as a function of magnetic field from -4 kOe to 4 kOe with a maximum magnetoelectric voltage coefficient of 10.7 mV ⋅ cm -1⋅ Oe -1 at the frequency of 1 kHz. It is a very high value in the lead-free magnetoelectric composites system for the potential use on multifunctional devices.

Correlation between Anomalous Peak Effect in Magnetic Hysteresis Loop and Nanoscale Structure forNdBa2Cu3O7-δSingle-Crystal Superconductor

1996 ◽  
Vol 35 (Part 1, No. 7) ◽  
pp. 3882-3886 ◽  
Author(s):  
Masaru Nakamura ◽  
Tsukasa Hirayama ◽  
Yasuji Yamada ◽  
Yuichi Ikuhara ◽  
Yuh Shiohara
Keyword(s):  
Hysteresis Loop ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Peak Effect ◽  
Anomalous Peak ◽  
Nanoscale Structure

Magnetic Hysteresis Loop of Single Co Nano-islands

2008 ◽  
Vol 47 (12) ◽  
pp. 9013-9015 ◽  
Author(s):  
Guillemin Rodary ◽  
Sebastian Wedekind ◽  
Dirk Sander ◽  
Jürgen Kirschner
Keyword(s):  
Hysteresis Loop ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop

scholarly journals Developing a reference material set for the magnetic properties of NdFeB alloy-based hard magnetic materials

2019 ◽  
Vol 15 (1) ◽  
pp. 21-27
Author(s):  
E. A. Volegova ◽  
T. I. Maslova ◽  
V. O. Vas’kovskiy ◽  
A. S. Volegov
Keyword(s):  
Magnetic Properties ◽  
Magnetic Materials ◽  
Permanent Magnets ◽  
Magnetic Loss ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Hysteresis Loop ◽  
Magnetic Characteristics ◽  
Hard Magnetic Materials ◽  
Certified Values

Introduction The introduction indicates the need for the use of permanent magnets in various technology fields. The necessity of measuring the limit magnetic hysteresis loop for the correct calculation of magnetic system parameters is considered. The main sources of error when measuring boundary hysteresis loops are given. The practical impossibility of verifying blocks of magnetic measuring systems element-by-element is noted. This paper is devoted to the development of reference materials (RMs) for the magnetic properties of hard magnetic materials based on Nd2Fe14B, a highly anisotropic intermetallic compound.Materials and measuring methods Nd-Fe-B permanent magnets were selected as the material for developing the RMs. RM certified values were established using a CYCLE‑3 apparatus included in the GET 198‑2017 State Primary Measurement Standard for units of magnetic loss power, magnetic induction of constant magnetic field in a range from 0.1 to 2.5 T and magnetic flux in a range from 1·10–5 to 3·10–2 Wb.Results and its discussion Based on the experimentally obtained boundary hysteresis loops, the magnetic characteristics were evaluated, the interval of permitted certified values was set, the measurement result uncertainty of certified values was estimated, the RM validity period was established and the first RM batch was released.Conclusion On the basis of conducted studies, the RM type for magnetic properties of NdFeB alloy-based hard magnetic materials was approved (MS NdFeB set). The developed RM set was registered under the numbers GSO 11059–2018 / GSO 11062–2018 in the State RM Register of the Russian Federation.

Ageing behavior study of 5Cr–0.5Mo steel by magnetic Barkhausen emissions and magnetic hysteresis loop techniques

2007 ◽  
Vol 40 (2) ◽  
pp. 173-178 ◽  
Author(s):  
J.N. Mohapatra ◽  
A.K. Panda ◽  
M.K. Gunjan ◽  
N.R. Bandyopadhyay ◽  
A. Mitra ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Behavior Study

Anisotropic critical current density and flux pinning mechanism of Fe1+yTe0.6Se0.4 single crystals

2021 ◽  
Author(s):  
Yongqiang Pan ◽  
Nan Zhou ◽  
Bencheng Lin ◽  
Jinhua Wang ◽  
Zengwei Zhu ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Pinning Force ◽  
Magnetization Relaxation ◽  
Pinning Mechanism

Abstract Fe1+yTe0.6Se0.4 has considerable application potential due to its large critical current density (J c) and high upper critical magnetic field (H c2). However, the uncertainty of the anisotropy of J c and the unclear flux-pinning mechanism have limited the application of this material. In this study, the J c in three directions were obtained from magnetic hysteresis loop measurements. A large anisotropy of J c ab /J c c ~ 10 was observed, and the origin of the anisotropy was discussed in details. Flux pinning force densities (F p) were obtained from J c, and a non-scaling behavior was found in the normalized pinning force f p[F p/F p-max] versus the normalized field h[H/H c2]. The peaks of pinning force shift from a high h to a low h with increasing temperature. Based on the vortex dynamics analysis, the peak shift was found to originate from the magnetization relaxation. The J c and F p at critical states free from the magnetic relaxation were regained. According to the Dew-Hughes model, the dominant pinning type in Fe1+yTe0.6Se0.4 clean single crystals was confirmed to be normal point pinning.

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