Optische Kernspin Polarisation (ONP) in Anthracen dotiert mit Phenazin im Temperaturbereich 1,4…300 K / Optical Nuclear Polarisation (ONP) in Anthracene doped with Phenazine in the Temperature Range 1.4…300 K

1977 ◽  
Vol 32 (6) ◽  
pp. 652-658 ◽  
Author(s):  
G. Dittrich ◽  
D. Stehlik ◽  
H. Hausser
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Zero Field ◽  
Triplet States ◽  
Prominent Feature ◽  
Zero Field Splitting ◽  
Principal Axes ◽  
Characteristic Features ◽  
Anthracene Crystal ◽  
The Magnetic Field

Abstract ONP of proton spins in anthracene doped with 1000 ppm phenazine has been measured as a function of the external magnetic field Hp and its orientation with respect to the crystalline axes for the temperatures: 300, 78, 4.2 and 1.4 K. At 300 K characteristic features in magnetic fields up to 150 G are similar to results observed in doped fluorene crystals. They are interpreted as due to ONP as a consequence of level anti-crossing (LAC) in the triplet state of guest-host complexes. The zero-field splitting tensor is: D*= ±0.0101 (2) cm-1, ∣E*∣≲∣ ± 0.000811 cm-1 with the principal axes z* ∥ b, y* and x* in the ac-plane with ∢ (y*, a) =30 + 1°. No complex formation is observed at or below 78 K.The most prominent feature at all temperatures is the field dependence of ONP when the magnetic field is oriented along the projection of the long molecular in-plane axes of the anthracene molecules. The excitable triplet states in the doped anthracene crystal are discussed in terms of their qualification as ONP-active states.

Magnetic Prehistory in the Heat Capacity of the Low-Temperature Superconductors

2015 ◽  
Vol 233-234 ◽  
pp. 741-744
Author(s):  
Sergey Mikhailovich Podgornykh
Keyword(s):  
Magnetic Field ◽  
Heat Capacity ◽  
External Magnetic Field ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Zero Magnetic Field ◽  
Zero Field ◽  
Ring Specimen ◽  
Trapped Flux ◽  
The Magnetic Field

Effect of the magnetic prehistory on the temperature dependence of the heat capacity of the superconducting Pb, La, Sn. has been studied. As soon as the external magnetic field riches the valueHext=HCthe superconductivity is completely destroyed. The trapped flux was produced in the ring specimen after the magnetic field was turned off atT<TC. We observed a difference of the value of the heat capacity between zero field cooled (ZFC) and field cooled (FC) states in zero magnetic field for the ring specimen. It is found that the FC heat capacity is smaller than the heat capacity both in the normal and in superconducting states.

SHOT NOISE OF ELECTRON PAIRS IN NONCYCLIC AND NON-ADIABATIC MAGNETIC FIELD

2007 ◽  
Vol 21 (17) ◽  
pp. 3065-3074
Author(s):  
XIAN-JUN YE
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Shot Noise ◽  
Beam Splitter ◽  
Rotating Magnetic Field ◽  
Triplet States ◽  
Electron Pairs ◽  
Singlet And Triplet States ◽  
The Magnetic Field ◽  
Symmetric Properties

By adding a rotating magnetic field in one incoming lead, we calculate the shot noise with different incident states in a 4-lead beam-splitter. The result shows that the shot noise of singlet and triplet states oscillates with the external magnetic field and depends on the symmetric properties of the incident states. Thus, the singlet, entangled triplet, and polarized states can be distinguished by adjusting the magnetic field.

Positive zero-field splitting and unexpected slow magnetic relaxation in the magneto-chemical calibrant HgCo(NCS)4

2021 ◽  
Vol 50 (10) ◽  
pp. 3468-3472
Author(s):  
Roman Boča ◽  
Ján Titiš ◽  
Cyril Rajnák ◽  
J. Krzystek
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Relaxation ◽  
Positive Zero ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Zero Field Splitting Parameter ◽  
Slow Magnetic Relaxation ◽  
Splitting Parameter

Magnetochemical standard HgCo(NCS)4 with positive zero-field splitting parameter D displays a slow magnetic relaxation strongly dependent upon the external magnetic field.

Simulations of Anisotropic Texture Evolution on Paramagnetic and Diamagnetic Materials Subject to a Magnetic Field Using Q-State Monte Carlo

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
J. B. Allen
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
External Magnetic Field ◽  
Grain Boundary ◽  
Boundary Energy ◽  
Magnetic Field Direction ◽  
Grain Boundary Energy ◽  
Average Grain Size ◽  
Principal Axes ◽  
The Magnetic Field

The present work incorporates a modified Q-state Monte Carlo (Potts) model to evaluate two-dimensional annealing of representative paramagnetic and diamagnetic polycrystalline materials in the presence of a magnetic field. Anisotropies in grain boundary energy, caused by differences in grain orientation (texturing), and the presence of an external magnetic field are examined in detail. In the former case, the Read–Shockley equations are used, in which grain boundary energies are computed using a low-angle misorientation approximation. In the latter case, magnetic anisotropy is simulated based on the relative orientation between the principal grain axis and the external magnetic field vector. Among other findings, the results of texture development subject to a magnetic field showed an increasing orientation distribution function (ODF) asymmetry over time, with higher intensities favoring the grains with principal axes most closely aligned with the magnetic field direction. The magnetic field also tended to increase the average grain size, which was accompanied by a corresponding decrease in the total grain boundary energy.

Magnetic field dependence of relaxation rates of non-Kramers doublets

1970 ◽  
Vol 48 (3) ◽  
pp. 355-361 ◽  
Author(s):  
M. B. Walker ◽  
F. I. B. Williams
Keyword(s):  
Magnetic Field ◽  
Field Dependence ◽  
Magnetic Field Dependence ◽  
Spin Lattice Relaxation ◽  
Zero Field ◽  
Relaxation Rates ◽  
Zero Field Splitting ◽  
Symmetry Properties ◽  
The Magnetic Field ◽  
Kramers Doublet

It was recently shown by one of the authors (MBW) that the second-order Raman process gives rise to an electron spin–lattice relaxation rate for non-Kramers ions varying as T5 at low temperatures. We determine here the magnetic field dependence of this relaxation process for a non-Kramers doublet. We find that, in contrast to the other Raman relaxation rates, the T5 rate has a frequency dependence [Formula: see text] where ω is the resonance frequency and Δ the zero-field splitting of the doublet. The magnetic field dependences of the various relaxation rates are shown to be consequences of the time-reversal symmetry properties of the non-Kramers doublet.

The Effect of Magnetic Field on the Hydration of Nanoscopic Hydrophobic N-Alkane Plates

2011 ◽  
Vol 228-229 ◽  
pp. 1007-1011
Author(s):  
Wei Wei Zhang ◽  
Long Qiu Li ◽  
Guang Yu Zhang ◽  
Hui Juan Dong
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Dynamics Simulation ◽  
Free Energy Barrier ◽  
Confined Water ◽  
Magnetic Exposure ◽  
Hydrophobic Solutes ◽  
The Magnetic Field ◽  
Density Of Water ◽  
Induced Adsorption

The effect of an external magnetic field on the hydration behavior of nanoscopic n-octane plates has been extensively investigated using molecular dynamics simulation in an isothermal-isobaric ensemble. The solute plates with different intermolecular spacing have also been considered to examine the effect of the topology of hydrophobic plates on the adsorption behavior of confined water in the presence of an external magnetic field with an intensity ranging from 0.1T to 1 T. The results demonstrate that magnetic exposure decreases the density of water for the plates with intermolecular spacing of a0 = 4 and 5 Å. This suggests that the free energy barrier for evaporation can be lowered by the applied field, and the hydrophobic solutes consisting of condensed n-octane molecules are apt to aggregate in the aqueous solution. In contrast, the magnetic field improves the dissolution or wetting of solutes comprised of loosely packed n-octane plates of a0=7Å. A magnetic-field-induced adsorption-to-desorption translation, which is in agreement with the experimental results provided by Ozeki, has also been observed for the plates with intermolecular spacing of a0 = 6 Å.

scholarly journals Reversibility of the Magnetocaloric Effect in the Bean-Rodbell Model

2021 ◽  
Vol 7 (5) ◽  
pp. 60
Author(s):  
Luis M. Moreno-Ramírez ◽  
Victorino Franco
Keyword(s):  
Magnetic Field ◽  
Thermal Hysteresis ◽  
Entropy Change ◽  
Second Order ◽  
Zero Field ◽  
First Order ◽  
Magnetic Field Change ◽  
Magnetocaloric Materials ◽  
Moderate Magnetic Field ◽  
The Magnetic Field

The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η<1 for second-order and η>1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η≈1.3−1.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones.

Zero-Field Level Crossing in the Helium Atom

1972 ◽  
Vol 50 (2) ◽  
pp. 116-118 ◽  
Author(s):  
C. W. T. Chien ◽  
R. E. Bardsley ◽  
F. W. Dalby
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Helium Atom ◽  
Cross Sections ◽  
Zero Field ◽  
Level Crossing ◽  
Field Level ◽  
Collision Cross Sections ◽  
The Magnetic Field

Zero-field level-crossing techniques have been used to measure some upper-state lifetimes of the helium atom. The half-widths of curves obtained by plotting the polarization against the magnetic field strength for the n1D–21D transitions yielded lifetimes of 2.03 × 10−8 s for the 31D state, 3.36 × 10−8 s for the 41D state, and 7.44 × 10−8 s for the 51D state. Collision cross sections for these 1D levels were also determined.

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