Experimental Studies of Magnetic Properties of Cuprates—from the Antiferromagnetic to Metallic State

2021 ◽  
pp. 207-269
Author(s):  
H Alloul
Keyword(s):  
Magnetic Properties ◽  
Experimental Studies ◽  
Metallic State

scholarly journals A research on magnetic properties of magnetic nanodispersed lubricants

2019 ◽  
Vol 298 ◽  
pp. 00015 ◽  
Author(s):  
Alexander Bolotov ◽  
Vladislav Novikov ◽  
Olga Novikova
Keyword(s):  
Magnetic Properties ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Oil Composition ◽  
Initial State ◽  
Optimal Operating ◽  
Composition And Structure ◽  
Friction Mode ◽  
Hall Sensors ◽  
Lubricating Properties

The paper presents the results of theoretical and experimental studies of the magnetic properties of magnetic lubricating oils. It shows oil magnetization curves in the initial state and after tests in the boundary friction mode. Oil properties were measured by an original magnetometer with Hall sensors. It has been established that triboeffects change oil composition and structure and decrease its magnetization. The results will help determine the optimal operating conditions of magnetic oils while maintaining their magnetic and lubricating properties.

π–d INTERACTION BASED MOLECULAR CONDUCTING MAGNETS: HOW TO INCREASE THE EFFECTS OF THE π–d INTERACTION

COSMOS ◽  
2008 ◽  
Vol 04 (02) ◽  
pp. 131-140 ◽  
Author(s):  
AKIRA MIYAZAKI ◽  
TOSHIAKI ENOKI
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Transition Temperature ◽  
Phase Boundary ◽  
Ground State ◽  
Magnetic Order ◽  
Molecular Magnets ◽  
Metallic State ◽  
One Dimensional

The crystal structures and electronic and magnetic properties of conducting molecular magnets developed by our group are reviewed from the viewpoints of our two current strategies for increasing the efficiency of the π–d interaction. (EDTDM)2 FeBr 4 is composed of quasi-one-dimensional donor sheets sandwiched between magnetic anion sheets. The ground state of the donor layer changes from the insulator state to the metallic state by the application of pressure. When it is near to the insulator–metal phase boundary pressure, the magnetic order of the anion spins considerably affects the transport properties of the donor layer. The crystal structure of ( EDO – TTFBr 2)2 FeX 4 ( X = Cl , Br ) is characterized by strong intermolecular halogen–halogen contacts between the organic donor and FeX 4 anion molecules. The presence of the magnetic order of the Fe 3+ spins and relatively high magnetic order transition temperature proves the role of the halogen–halogen contacts as exchange interaction paths.

scholarly journals A study of the magnetic properties in the Hubbard model on the honeycomb lattice by variational cluster approximation

2016 ◽  
Vol 30 (23) ◽  
pp. 1650158 ◽  
Author(s):  
Atsushi Yamada
Keyword(s):  
Magnetic Properties ◽  
Hubbard Model ◽  
Quantum Monte Carlo ◽  
Large Scale ◽  
Interaction Strength ◽  
Honeycomb Lattice ◽  
Metallic State ◽  
Cluster Approximation ◽  
Nonmagnetic Metal ◽  
Variational Cluster Approximation

Magnetic properties of the half-filled Hubbard model on the honeycomb lattice, which is a simple model of graphene, are studied using the variational cluster approximation (VCA). We found that the critical interaction strength of a magnetic transition is slightly lower than that of the nonmagnetic metal-to-insulator transition and the magnetic order parameter is already nonnegligible at the latter transition point. Thus, a semi-metallic state becomes a magnetic insulator as the interaction strength increases, and a spin liquid state characterized by a Mott insulator without spontaneously broken spatial or spin symmetry, or a state very close to that is not realized in this system. Both the magnetic and nonmagnetic metal-to-insulator transitions are of the second-order. Our results agree with recent large scale quantum Monte Carlo (QMC) simulations.

Hydroxyapatite substituted by transition metals: experiment and theory

2016 ◽  
Vol 18 (24) ◽  
pp. 16457-16465 ◽  
Author(s):  
M. E. Zilm ◽  
L. Chen ◽  
V. Sharma ◽  
A. McDannald ◽  
M. Jain ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Transition Metal ◽  
Transition Metals ◽  
Experimental Studies ◽  
Theoretical Predictions

Experimental studies and theoretical predictions have been conducted to investigate magnetic properties of transition metal-substituted hydroxyapatite.

scholarly journals Influence of Molecular Orbitals on Magnetic Properties of FeO2Hx

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2211 ◽  
Author(s):  
Alexey O. Shorikov ◽  
Sergey L. Skornyakov ◽  
Vladimir I. Anisimov ◽  
Sergey V. Streltsov ◽  
Alexander I. Poteryaev
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Mean Field Theory ◽  
Mean Field ◽  
Molecular Orbitals ◽  
Metallic State ◽  
Functional Theory ◽  
High Pressure And Temperature ◽  
Fe Ions ◽  
Mass Enhancement

Recent discoveries of various novel iron oxides and hydrides, which become stable at very high pressure and temperature, are extremely important for geoscience. In this paper, we report the results of an investigation on the electronic structure and magnetic properties of the hydride FeO 2 H x , using density functional theory plus dynamical mean-field theory (DFT+DMFT) calculations. An increase in the hydrogen concentration resulted in the destruction of dimeric oxygen pairs and, hence, a specific band structure of FeO 2 with strongly hybridized Fe- t 2 g -O- p z anti-bonding molecular orbitals, which led to a metallic state with the Fe ions at nearly 3+. Increasing the H concentration resulted in effective mass enhancement growth which indicated an increase in the magnetic moment localization. The calculated static momentum-resolved spin susceptibility demonstrated that an incommensurate antiferromagnetic (AFM) order was expected for FeO 2 , whereas strong ferromagnetic (FM) fluctuations were observed for FeO 2 H.

Structural, Electronic and Magnetic Properties of GaMnN, MnN and Rare-Earth Nitride Thin Films

2021 ◽  
Author(s):  
◽  
Simon Granville
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Rare Earth ◽  
Diluted Magnetic Semiconductor ◽  
Experimental Studies ◽  
Magnetic Semiconductor ◽  
Electronic And Magnetic Properties ◽  
Rare Earth Nitrides ◽  
Diluted Magnetic ◽  
Reaction With Water

<p>Materials that combine the useful properties of magnetic and semiconducting behaviours are sought for new and developing applications in electronics. In this thesis experimental studies of the properties of disordered thin films of several potentially magnetic semiconducting materials are presented. Previous research on the diluted magnetic semiconductor GaMnN is reviewed as an introduction to a study of GaMnN thin films grown with an ion-assisted deposition technique. Several complementary compositional and structural analysis techniques are used to determine that films can be grown with as much as 18 at. % Mn content and that contain no impurity phases, as are often detected in single crystalline GaMnN preparations with high Mn concentrations. The effects of varying Mn contents on the resistive, optical and magnetic properties of the thin films are investigated. The structural, electronic and magnetic properties of thin films of the potential impurity phase MnN have also been investigated and compared with band structure calculations. Recent predictions that the rare earth nitrides may have extremely useful electronic properties have been almost untested in the literature. A procedure for growing rare earth nitride thin films and capping them to protect from reaction with water vapour allows their resistivity, structural and magnetic properties to be established. The results on GdN, SmN, ErN and DyN support the recent predictions, and a more thorough study on GdN reveals that this material is a ferromagnetic semiconductor below 69 K.</p>

Praseodymium and Neodymium-Based Nanocrystalline Hard Magnetic Alloys

1999 ◽  
Vol 577 ◽  
Author(s):  
H.A. Davies ◽  
C.L. Harland ◽  
R.J.I. Betancour ◽  
S.G. Mendoza
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Melt Spinning ◽  
Experimental Studies ◽  
Anisotropy Field ◽  
Partial Substitution ◽  
Magnetic Alloys ◽  
Alloy Systems

ABSTRACTThe magnetic properties of nanophase exchange enhanced RE-Fe-B based alloys ribbons prepared by melt spinning are presented and discussed. The alloy systems investigated include NdyFe94−yB6 and PryFe94−yB6, for y within the range 6-20 at%, and the data are compared in the context of the larger anisotropy field for the Pr2Fe14B phase in comparison with Nd2Fe14B. Experimental studies are also reported for nanophase (Nd-Pr)- Fe-B alloys with various proportions of Nd:Pr, to investigate the increase in coercivity of NdFeB by partial substitution of Nd by Pr, and for (Nd, Pr)-(Fe-Co)-B-based systems, to study the degree to which the remanence enhancement can be maintained for alloys in which Co substitutes for Fe to increase the thermal stability.

Investigating magnetic properties of Co68Fe4B15Si13 amorphous alloy by molecular dynamics and DFT calculations

2017 ◽  
Vol 31 (09) ◽  
pp. 1750094
Author(s):  
R. Mardani ◽  
M. R. Kazerani ◽  
H. Shahmirzaee
Keyword(s):  
Molecular Dynamics ◽  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Density Functional ◽  
Rational Design ◽  
Wide Spectrum ◽  
Dipole Moments ◽  
Experimental Studies ◽  
Functional Theory ◽  
Electronic And Magnetic Properties

Cobalt-based amorphous alloys, in particular CoFeBSi, have been widely used to study the response of ac-impedance to the external dc magnetic field, i.e., the so-called Giant Magneto Impedance (GMI) effect. The utility of CoFeBSi in different applications such as field-sensitive sensors is known and practiced. Despite the wealth of experimental studies on GMI properties of CoFeBSi alloys, no computational approach has yet been addressed on electronic and magnetic properties of these systems at nanoscales. In this study, we have computed electronic and magnetic properties of amorphous CoFeBSi alloys using a combined Molecular Dynamics (MD) and Density Functional Theory (DFT) approach. MD is used to provide a physically realistic sampling of different atomic configurations while the properties such as dipole moments and magnetic susceptibilities are computed using DFT. Our study shows a wide spectrum of electronic as well as magnetic properties for nanoclusters of different sizes having implications for rational design of Co-based ferromagnetic alloys.

scholarly journals Monte Carlo and Experimental Magnetic Studies of Molecular Spintronics Devices

NANO ◽  
2015 ◽  
Vol 10 (04) ◽  
pp. 1550056 ◽  
Author(s):  
Pawan Tyagi ◽  
Christopher D'Angelo ◽  
Collin Baker
Keyword(s):  
Monte Carlo ◽  
Magnetic Properties ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Magnetic Tunnel Junction ◽  
Magnetic Interactions ◽  
Magnetic Studies ◽  
Magnetic Molecules ◽  
Wide Range ◽  
Different Temperatures

Molecule-based spintronics devices (MSDs) are highly promising candidates for discovering advanced logic and memory computer units. An advanced MSD will require the placement of paramagnetic molecules between the two ferromagnetic (FM) electrodes. Due to extreme fabrication challenges, only a couple of experimental studies could be performed to understand the effect of magnetic molecules on the overall magnetic and transport properties of MSDs. To date, theoretical studies mainly focused on charge and spin transport aspects of MSDs; there is a dearth of knowledge about the effect of magnetic molecules on the magnetic properties of MSDs. This paper investigates the effect of magnetic molecules, with a net spin, on the magnetic properties of 2D MSDs via Monte Carlo (MC) simulations. Our MC simulations encompass a wide range of MSDs that can be realized by establishing different kinds of magnetic interactions between molecules and FM electrodes at different temperatures. The MC simulations show that ambient thermal energy strongly influenced the molecular coupling effect on the MSD. We studied the nature and strength of molecule couplings (FM and antiferromagnetic) with the two electrodes on the magnetization, specific heat and magnetic susceptibility of MSDs. For the case when the nature of molecule interaction was FM with one electrode and antiferromagnetic with another electrode the overall magnetization shifted toward zero. In this case, the effect of molecules was also a strong function of the nature and strength of direct coupling between FM electrodes. In the case when molecules make opposite magnetic couplings with the two FM electrodes, the MSD model used for MC studies resembled with the magnetic tunnel junction based MSD. The experimental magnetic studies on these devices are in agreement with our theoretical MC simulations results. Our MC simulations will enable the fundamental understanding and designing of a wide range of novel spintronics devices utilizing a variety of molecules, nanoclusters and quantum dots as the device elements.

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