scholarly journals EXCHANGE COUPLING AND DECOUPLING IN A NANOCOMPOSITE SPIN SYSTEM

2006 ◽  
Vol 20 (01) ◽  
pp. 61-72 ◽  
Author(s):  
Y. Z. SHAO ◽  
W. R. ZHONG ◽  
T. LAN ◽  
R. H. LEE
Keyword(s):  
Magnetic Property ◽  
Spin System ◽  
Exchange Coupling ◽  
Lattice Structure ◽  
Magnetic Behavior ◽  
Reduced Form ◽  
Single Spin ◽  
Spin Lattice ◽  
Lower Temperature ◽  
Heterogeneous Ensemble

We studied the exchange coupling and decoupling process in a nanocomposite spin system based on a 3D Heisenberg model by means of Monte Carlo numerical computation simulation. Different from the conventional micromagnetism approach in which finite elements method (FEM) is usually adopted to compute, in a top-down way, the magnetic property of micromagnetic ensemble in micron even nanometer scale our current paper presents a new approach in computing the magnetic property of above nanomagnetic ensemble. Our approach addressed a composite spin lattice structure consisting of both single spin and cluster spin built up from single spin in a bottom-up way. Two species of distinctive spins were taken into account further in order to imitate the magnetic behavior of heterogeneous ensemble. The simulation revealed the influence of exchange coupling constant Jab, the size of cluster spins d and system reduced temperature t upon the exchange coupling and decoupling between component spin phases, respectively. Smaller value of Jab, larger d and lower temperature t usually lead to the decoupling of originally exchange-coupled component phases and the occurrence of a characteristic two-stage shoulder with an inflexion on the demagnetization curve. The results reported here are, to some extent, of universality and applicable to other dual-phase magnetic systems since our simulation simply focus on a pure duplex spin system rather than a specific material, and all physical variables were treated in a reduced form.

Tetranuclear copper(ii) cubane complexes derived from self-assembled 1,3-dimethyl-5-(o-phenolate-azo)-6-aminouracil: structures, non-covalent interactions and magnetic property

2021 ◽  
Vol 45 (5) ◽  
pp. 2742-2753
Author(s):  
Nishithendu Bikash Nandi ◽  
Atanu Purkayastha ◽  
Shaktibrata Roy ◽  
Julia Kłak ◽  
Rakesh Ganguly ◽  
...  
Keyword(s):  
Magnetic Property ◽  
Exchange Coupling ◽  
Antiferromagnetic Exchange ◽  
Non Covalent Interactions ◽  
Cubane Cluster ◽  
Self Assembled ◽  
Covalent Interactions

A new doubly opened 4 + 2 Cu4O4 cubane cluster exhibits strong antiferromagnetic exchange coupling with J1 = −110.1 cm−1, and J2 = −27.1 cm−1.

Spin-Lattice Coupling and Peculiarities of Magnetic Behavior of Ferrimagnetic Ludwigites Mn0.52+M1.52+Mn3+BO5(M=Cu, Ni)

2015 ◽  
Vol 233-234 ◽  
pp. 133-136 ◽  
Author(s):  
Leonard Bezmaternykh ◽  
Evgeniya Moshkina ◽  
Evgeniy Eremin ◽  
Maxim Molokeev ◽  
Nikita Volkov ◽  
...  
Keyword(s):  
Temperature Field ◽  
Low Temperature ◽  
Magnetic Anisotropy ◽  
Single Crystals ◽  
Magnetic Behavior ◽  
Temperature Hysteresis ◽  
Spin Lattice ◽  
Field Magnetization ◽  
Lattice Coupling

Temperature-field and orientational magnetization dependences of single crystals were measured. Both samples demonstrate significant field-depending temperature hysteresis and low-temperature counter field magnetization. The correlation of orientational dependences of these effects and magnetic anisotropy is analyzed; the role of spin-lattice interactions is discussed.

Calculation of NQR v's and T1-1' s being proportional to T4 and T5 , respectively

1990 ◽  
Vol 45 (3-4) ◽  
pp. 536-540
Author(s):  
Mariusz Máckowiak ◽  
Costas Dimitropoulos
Keyword(s):  
Temperature Dependence ◽  
Relaxation Rate ◽  
Spin System ◽  
Low Frequency ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Lattice Vibrations ◽  
Spin Lattice ◽  
Simplifying Assumptions ◽  
The One

Abstract The second-order Raman phonon process for a multilevel spin system is shown to give a quadru-polar spin-lattice relaxation rate T1-1varying as T5 at very low temperatures. This relaxation rate for quadrupole spins is similar to the one discussed for a paramagnetic spin system having a multilevel ground state. The temperature dependence of T1 is discussed on the basis of some simplifying assumptions about the nature of the lattice vibrations in the Debye approximation. This type of relaxation process has been observed below 20 K in tetramethylammonium hydrogen bis-trichloroacetate for the 35Cl T1-1 . Below 20 K the NQR frequency in the same crystal reveals a T4 temperature dependence due to the induced modulations of the vibrational and librational coordinates by the low-frequency acoustic phonons.

scholarly journals Observation of Charge Ordering Signal in Monovalent Doped Nd0.75Na0.25-xKxMn1O3 (0 ≤ x ≤ 0.10) Manganites

2018 ◽  
Vol 7 (4.30) ◽  
pp. 85
Author(s):  
Sufia Aqilah Razali ◽  
Norazilah Ibrahim ◽  
Suhadir Shamsuddin ◽  
Mohamad Zaky Noh
Keyword(s):  
Crystalline Phase ◽  
Electrical Transport ◽  
Resistivity Measurement ◽  
Magnetic Behavior ◽  
Charge Ordering ◽  
Ferromagnetic Phase ◽  
Electrical Resistivity Measurement ◽  
Diffraction Measurement ◽  
The Difference ◽  
Lower Temperature

K doping in the compound of Nd0.75Na0.25-xKxMn1O3 (x = 0, 0.05 and 0.10) manganites have been investigated to study its effect on crystalline phase and surface morphology as well as electrical transport and magnetic properties. The structure properties of the Nd0.75Na0.25-xKxMnO3 manganite have been characterized using X-ray diffraction measurement and it proved that the crystalline phase of samples were essentially single phased and indexed as orthorhombic structure with space group of Pnma. The morphological study from scanning electron microscope showed there was an improvement on the grains boundaries and sizes as well as the compactness with K doping suggestively due to the difference of ionic radius. On the other hand, DC electrical resistivity measurement showed all samples exhibit insulating behavior. However, analysis of dlnρ/dT-1 vs. T revealed the clearly peaks could be observed at temperature 210K for x = 0 and the peaks were shifted to the lower temperature around 190 K and 165 K for x = 0.05 and x = 0.1 respectively, indicate the existence of charge ordering (CO) state in the compound. Meanwhile, the investigation on magnetic behavior showed all samples exhibit transition from paramagnetic phase to anti-ferromagnetic phase with decreasing temperature and the TN was observed to shift to lower temperature suggestively due to weakening of CO state

Molecular dynamics simulation of aggregation of monocrystal and polycrystal copper nanoparticles

2019 ◽  
Vol 33 (16) ◽  
pp. 1950168
Author(s):  
Linxing Zhang ◽  
Guang Hong ◽  
Shouyin Cai
Keyword(s):  
Molecular Dynamics ◽  
Lattice Structure ◽  
Displacement Vector ◽  
Mean Square Displacement ◽  
Dynamics Simulation ◽  
Gyration Radius ◽  
Mean Square ◽  
Shrinkage Ratio ◽  
Lower Temperature ◽  
Dynamics Simulations

Molecular dynamics simulations were employed to investigate the aggregation of monocrystal and polycrystal nanoparticles. The lattice structure, displacement vector, potential energy, shrinkage ratio, relative gyration radius and mean square displacement of the two systems are compared. The results indicate that the aggregation of polycrystal nanoparticles is more drastic than that of monocrystal nanoparticles. Besides, the polycrystal nanoparticles are found contacted and melted at lower-temperature than that of monocrystal nanoparticles. The reason for all these phenomena is that there is additional surface energy in the grain boundary of polycrystal nanoparticles.

Magnetism of Spin System with Alternating Strong and Weak Exchange Coupling. I. Theoretical Study

1981 ◽  
Vol 50 (11) ◽  
pp. 3583-3587 ◽  
Author(s):  
Shigeru Takatori ◽  
Naoshi Suzuki ◽  
Kazuko Motizuki
Keyword(s):  
Spin System ◽  
Exchange Coupling ◽  
Theoretical Study ◽  
Weak Exchange

scholarly journals Yu-Shiba-Rusinov bands in ferromagnetic superconducting diamond

2020 ◽  
Vol 6 (20) ◽  
pp. eaaz2536
Author(s):  
Gufei Zhang ◽  
Tomas Samuely ◽  
Naoya Iwahara ◽  
Jozef Kačmarčík ◽  
Changan Wang ◽  
...  
Keyword(s):  
Lattice Structure ◽  
Three Dimensional ◽  
Superconducting Devices ◽  
Electronic States ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Boron Doped Diamond ◽  
Spin Lattice ◽  
Boron Doped ◽  
Potential Applications

The combination of different exotic properties in materials paves the way for the emergence of their new potential applications. An example is the recently found coexistence of the mutually antagonistic ferromagnetism and superconductivity in hydrogenated boron-doped diamond, which promises to be an attractive system with which to explore unconventional physics. Here, we show the emergence of Yu-Shiba-Rusinov (YSR) bands with a spatial extent of tens of nanometers in ferromagnetic superconducting diamond using scanning tunneling spectroscopy. We demonstrate theoretically how a two-dimensional (2D) spin lattice at the surface of a three-dimensional (3D) superconductor gives rise to the YSR bands and how their density-of-states profile correlates with the spin lattice structure. The established strategy to realize new forms of the coexistence of ferromagnetism and superconductivity opens a way to engineer the unusual electronic states and also to design better-performing superconducting devices.

COMPARISON OF MAGNETIC PROPERTY OF Cu-, Al-, AND Li-DOPED ZnO DILUTE MAGNETIC SEMICONDUCTOR THIN FILMS

2008 ◽  
Vol 15 (01n02) ◽  
pp. 81-85 ◽  
Author(s):  
L. H. VAN ◽  
J. DING ◽  
M. H. HONG ◽  
Z. C. FAN ◽  
L. WANG
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Magnetic Property ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Dilute Magnetic Semiconductor ◽  
Magnetic Semiconductor ◽  
Semiconductor Thin Films ◽  
Doped Zno ◽  
Lower Temperature

The properties of Cu -, Al -, and Li -doped ZnO dilute magnetic semiconductor (DMS) have been analyzed and compared. Zincite with wurtzite structures have been synthesized successfully on SiO 2 (101) and SiO 2 (110) substrates in both the Cu – ZnO and Li – ZnO DMS. The highly textured ZnO (002) peaks were able to form in the Cu – ZnO system at 400°C. However, it formed at even much lower temperature in the Li – ZnO system, that is only 25°C. ZnO (002) peaks in both systems were formed without any impurity phases. However, no crystalline structure is synthesized in the Al – ZnO system. The thin films formed are amorphous. The structural and related magnetic properties of the films were analyzed by XRD, AFM, and VSM. The films were found to be at their highest magnetism at the value of 3.1 emu/cm3 for Co – ZnO and 2.5 emu/cm3 for Li – ZnO , synthesized at 400°C, and under 1 × 10-4 Torr oxygen partial pressure.

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