Possible gapless chiral phase in a frustrated S = 1 1D anti-ferromagnet, CaV2O4

2001 ◽  
Vol 79 (11-12) ◽  
pp. 1551-1555 ◽  
Author(s):  
H Kikuchi ◽  
M Chiba ◽  
T Kubo
Keyword(s):  
Magnetic Susceptibility ◽  
Spin Chain ◽  
Chiral Phase ◽  
Spin Gap ◽  
Spin Freezing ◽  
Model Substance ◽  
Theoretical Predictions ◽  
Ferromagnetic Interactions ◽  
Theoretical Results ◽  
Broad Region

We have measured magnetic susceptibility and 51V NMR of CaV2O4, a model substance for a frustrated S = 1 spin chain with competing first- and second-neighbor anti-ferromagnetic interactions. Both the low-temperature magnetic susceptibility and the NMR Knight shift did not go down to zero as the temperature was lowered, suggesting that a spin gap is not present in CaV2O4. The absence of a spin gap gives us a clear contrast to the case of the nonfrustrated spin chains, which should have the Haldane gap. Recently published theoretical results for S = 1 XY or XXZ spin chain indicate that the gapless chiral phase could appear in a relatively broad region. Experimental results are discussed in terms of these theoretical predictions. A spin-freezing anomaly was observed at 20 K, reflecting the spin-frustrating nature of the system. PACS Nos.: 75.30, 75.50

The Convergence of the H-P Version of the Finite Element Method with Quasi-Uniform Meshes for Three Dimensional Poisson Problems with Edge Singularity

2014 ◽  
Vol 644-650 ◽  
pp. 1551-1555
Author(s):  
Jian Ming Zhang ◽  
Yong He
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Weighted Sobolev Spaces ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Smooth Functions ◽  
Edge Singularity ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Element Method

This paper is concerned with the convergence of the h-p version of the finite element method for three dimensional Poisson problems with edge singularity on quasi-uniform meshes. First, we present the theoretical results for the convergence of the h-p version of the finite element method with quasi-uniform meshes for elliptic problems on polyhedral domains on smooth functions in the framework of Jacobi-weighted Sobolev spaces. Second, we investigate and analyze numerical results for three dimensional Poission problems with edge singularity. Finally, we verified the theoretical predictions by the numerical computation.

Ferromagnetic interactions in a dicyanamide-bridged multinuclear metal-organic framework [Pr3NH]+ [Mn(dca)3]−·H2O

2019 ◽  
Vol 74 (6) ◽  
pp. 485-489
Author(s):  
Yuan Huang ◽  
Xiu-feng Yu ◽  
Zhen Rong ◽  
Yi-chun Ai ◽  
Kun Qian ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Measurements ◽  
Metal Organic Framework ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Magnetic Susceptibility Data ◽  
X Ray ◽  
Susceptibility Data ◽  
Metal Organic ◽  
Ferromagnetic Interactions

AbstractA new complex [Pr3NH]+ [Mn(dca)3]− · H2O (dicyanamide = dca−) was synthesized, in which the Mn2+ cations are bridged by end-to-end dca anions to form three-dimensional [Mn(dca)3]nn− networks and tripropylammonium cations reside in the cavities of these networks. The complex has been characterized by single-crystal X-ray diffraction, infrared spectroscopy, elemental analysis, and magnetic measurements. Magnetic susceptibility data indicate ferromagnetic interactions among the MnII ions.

Experimental and theoretical fatigue-crack propagation lives of variously notched plates

1974 ◽  
Vol 9 (2) ◽  
pp. 61-66 ◽  
Author(s):  
R A Smith ◽  
K Jerram ◽  
K J Miller
Keyword(s):  
Fatigue Life ◽  
Crack Propagation ◽  
Finite Element Analyses ◽  
Intensity Factors ◽  
Complex Profile ◽  
Propagation Law ◽  
Theoretical Predictions ◽  
Life Predictions ◽  
Theoretical Results

The fatigue lives of variously notched plates have been determined theoretically and experimentally. Theoretical predictions of fatigue lives involved the determination of stress-intensity factors from finite-element analyses. By invoking a crack propagation law, fatigue-life predictions were made for four specimens. Fatigue experiments were conducted on four notched plates subjected to end load plus bending. Comparison with theoretical results shows that the experimental lives were greater by factors of 1.30 to 1.54. These results are most satisfactory since (1) a safe prediction of fatigue life has been made for a complex profile subjected to non-simple loading conditions, and (2) a theoretical elastic analysis has sufficed for a situation involving plastic strains.

scholarly journals Magnetic anomalies in the spin-chain compoundSr3CuRhO6: Griffiths-phase-like behavior of magnetic susceptibility

2007 ◽  
Vol 75 (5) ◽  
Author(s):  
E. V. Sampathkumaran ◽  
Niharika Mohapatra ◽  
Sudhindra Rayaprol ◽  
Kartik K. Iyer
Keyword(s):  
Magnetic Susceptibility ◽  
Spin Chain ◽  
Magnetic Anomalies ◽  
Griffiths Phase

Thermal Behavior and Friction in Journal Bearings

1970 ◽  
Vol 92 (3) ◽  
pp. 373-380 ◽  
Author(s):  
Al. Nica
Keyword(s):  
Experimental Data ◽  
Thermal Behavior ◽  
Heat Dissipation ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Characteristics ◽  
Lubricant Flow ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with friction and the field of temperature in the lubricant film of journal bearings. Theoretical results regarding the thermal behavior are checked with experimental data and good agreement is found. Emphasis is put on the variation of temperature and lubricant flow with the operating characteristics of the bearing and it is seen that theoretical predictions for minima of friction torque are backed by temperature measurements. Further on, the friction torque and the mechanism of heat dissipation in bearings are dealt with, in order to verify the assumptions used in the calculation schemes. The means of efficiently cooling the bearing are also discussed, as well as the part played by the divergent zone in this process.

scholarly journals [CrIII8NiII6]n+ Heterometallic Coordination Cubes

2021 ◽  
Author(s):  
Helen O'Connor ◽  
Sergio Sanz ◽  
Aaron Scott ◽  
Mateusz Pitak ◽  
Wim Klooster ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Direct Current ◽  
Zero Field ◽  
Modular Approach ◽  
Zero Field Splitting ◽  
Heterometallic Clusters ◽  
Related Family ◽  
Weak Exchange ◽  
Ferromagnetic Interactions ◽  
Weak Ferromagnetic

Three new heterometallic [CrIII8NiII6] coordination cubes of formulae [CrIII8NiII6L24(H2O)12](NO3)12 (1), [CrIII8NiII6L24(MeCN)7(H2O)5](ClO4)12 (2) and [CrIII8NiII6L24Cl12] (3) (where HL = 1-(4-pyridyl)butane-1,3-dione), were synthesised using the paramagnetic metalloligand [CrIIIL3] and the corresponding NiII salt. The magnetic skeleton of each capsule describes a face-centred cube in which the eight CrIII and six NiII ions occupy the eight vertices and six faces of the structure, respectively. Direct current magnetic susceptibility measurements on (1) reveal weak ferromagnetic interactions between the CrIII and NiII ions, with JCr-Ni = +0.045 cm-1 . EPR spectra are consistent with weak exchange, being dominated by the zero-field splitting of the CrIII ions. Excluding wheel-like structures, examples of large heterometallic clusters containing both CrIII and NiII ions are rather rare, and we demonstrate that the use of metalloligands with predictable bonding modes allows for a modular approach to building families of related polymetallic complexes. Compounds (1)-(3) join the previously published, structurally related family of [MIII8MII6] cubes, where MIII = Cr, Fe and MII = Cu, Co, Mn, Pd. <br>

Ligand-Field Calculations on Pseudo-Tetragonal High-Spin Fe(II) Compounds

1977 ◽  
Vol 32 (12) ◽  
pp. 1404-1418
Author(s):  
A. Vermaas ◽  
W. L. Groeneveld ◽  
J. Reedijk
Keyword(s):  
Experimental Data ◽  
Magnetic Susceptibility ◽  
Room Temperature ◽  
Point Group ◽  
Point Symmetry ◽  
Ligand Field ◽  
Ligand Field Theory ◽  
State Splitting ◽  
Ligand Field Spectra ◽  
Theoretical Results

Abstract The compounds Fe(pz)4X2 and Fe(mpz)4X2, where pz stands for pyrazole, mpz for 5-methyl-pyrazole and X means Cl, Br or I, have been investigated by magnetic susceptibility, magnetic saturation and Mössbauer spectroscopy. The experimental temperatures vary from 2K to room temperature for the magnetic susceptibility measurements and from 4K to room temperature for the Mössbauer measurements. Mössbauer spectra in an applied magnetic field are also reported. The results of both types of measurements and ligand-field spectra are interpreted using a ligand-field theory. The tetragonal ground-state splitting parameters have been determined using the ligand-field spectra. For the pyrazole compounds, the experimental data nicely agree with theoretical results. The quadrupole splitting and the magnetic properties of these com­ pounds can be completely described within the used model, assuming a tetragonal molecular point symmetry. For the 5-methylpyrazole compounds, the measurements show that the point symmetry is lower than tetragonal. The agreement between the experimental data and the theoretical results for a point group Ci is less fair, especially concerning the Vzz and η values. Besides the Vzz values of Fe(mpz)4X2 differ significantly from those of the corresponding Fe(pz)4X2 compounds.

Novel spin-dimer system of a microporous polyborate NaCuB7O12.nH2O

2007 ◽  
Vol 1032 ◽  
Author(s):  
Jing Ju ◽  
Juns Sasaki ◽  
Naoki Toyota ◽  
Katsumi Tanigaki
Keyword(s):  
Magnetic Susceptibility ◽  
Boric Acid ◽  
Exchange Interaction ◽  
Interaction Constant ◽  
Membered Ring ◽  
Magnetic Susceptibility Data ◽  
Susceptibility Data ◽  
Spin Dimer ◽  
Theoretical Predictions

AbstractA new microporous polyborate, NaCuB7O12.nH2O, is synthesized using boric acid as a flux. It contains a 14-membered ring framework built up by CuO6 octahedra, BO4 tetrahedra and BO3 triangles. The spin-1/2 dimers of Cu2+ ions are connected by BO3 to form an infinite ladder along the b-axis. Magnetic susceptibility data between 2 and 330 K are presented, and the data are accurately fitted by theoretical predictions of Bleaney-Bowers for the spin-1/2 dimer, with J/kB = -153.8 K, and g = 1.98, where J is the intradimer exchange interaction constant and g is the Landé g factor.

Step Response Characteristics of Hydrostatic Journal Bearings With Self-Controlled Restrictors Employing a Floating Disk

1999 ◽  
Vol 121 (2) ◽  
pp. 315-320 ◽  
Author(s):  
S. Yoshimoto ◽  
K. Kikuchi
Keyword(s):  
Static Load ◽  
Journal Bearings ◽  
Step Response ◽  
Design Parameters ◽  
Static Stiffness ◽  
Load Direction ◽  
Response Characteristics ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Very High

This paper describes the step response characteristics of hydrostatic journal bearings with self-controlled restrictors employing a floating disk. This type of bearing can achieve very high static stiffness by controlling the mass flow rate of the fluid entering the bearing clearance using a floating disk. Many design parameters such as supply pressure, viscosity, the magnitude of the step load and the imposed static load affect the step response characteristics of the proposed bearing. Therefore, the influences of each design parameter on the step response characteristics are theoretically investigated in this paper. Furthermore, the theoretical results are compared with the experimental results in order to verify the theoretical predictions. It is subsequently found that the proposed bearing consistently shows a stable step response irrespective of the step-load direction.

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