SEMICLASSICAL THEORY OF PHONON RADIATION PROCESSES

1966 ◽  
Vol 44 (8) ◽  
pp. 1699-1714 ◽  
Author(s):  
J. Van Kranendonk
Keyword(s):  
Time Derivative ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Multipole Moments ◽  
Spin Variable ◽  
Effective Spin ◽  
Spin Lattice ◽  
Radiation Theory ◽  
Order Of Magnitude ◽  
Radiation Processes

For the various forms of the spin-lattice coupling in paramagnetic salts of the iron group ions, derived in a previous paper, a semiclassical phonon radiation theory is developed. The phonon fields are analyzed in terms of phonon multipole fields, and the phonon multipole moments are expressed in terms of the effective spin variable. The phonon multipole fields are all monopole fields in the sense that the corresponding static fields fall off at large distances as R−2, but they are monopole, dipole, and quadrupole fields as far as the angular dependence is concerned. As a result, the rates of emission by the different phonon multipoles are all of the same order of magnitude. The equation of motion of a dressed spin is derived, and the phonon radiation damping is shown to depend on the third time derivative of the phonon multipole moments. As an application, the classical theory of the resulting spin-lattice relaxation is discussed briefly.

A Nuclear Spin Relaxation Study of the Spin–Rotation Interaction in Symmetric Top Molecules

1972 ◽  
Vol 50 (12) ◽  
pp. 1262-1272 ◽  
Author(s):  
Robin L. Armstrong ◽  
James A. Courtney
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Spin Rotation ◽  
Spin Lattice Relaxation ◽  
Molecular Reorientation ◽  
Effective Spin ◽  
Spin Lattice ◽  
Simple Exponential Function ◽  
Symmetric Top Molecules

The spin–lattice relaxation times T1 of 1H, 19F, and 31P nuclei were measured in gaseous samples of BF3, CHF3, CH3F, PH3, and NH3 at room temperature for densities from 0.03 to 10 amagat. In several cases the behavior of T1 at the lowest densities snowed deviations from the linear variation characteristic of the extreme narrowing region. The spin–rotation interaction provides the dominant relaxation mechanism in all cases. The data are analyzed on the basis of the assumption that the collision modulated spin–rotation interaction may be described by a single correlation function which is a simple exponential function of time. Values of an effective spin–rotation constant and a cross section for molecular reorientation are obtained for each gas. The results obtained are compared with those available from other types of experiments. This comparison indicates that the theory for spin–lattice relaxation in dilute gases of symmetric top molecules needs to be carefully reassessed.

scholarly journals Clock Transition Due to a Record 1240 G Hyperfine Interaction in a Lu(II) Molecular Spin Qubit

2021 ◽  
Author(s):  
Krishnendu Kundu ◽  
Jessica R. K. White ◽  
Samuel A. Moehring ◽  
Jason M. Yu ◽  
Joseph W. Ziller ◽  
...  
Keyword(s):  
Hyperfine Interaction ◽  
Self Assembly ◽  
Scale Up ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Clock Transition ◽  
Spin Lattice ◽  
Memory Time ◽  
Order Of Magnitude ◽  
Orbital Character

Spins in molecules are particularly attractive targets for next-generation quantum technologies, enabling chemically programmable qubits and potential for scale-up via self-assembly. Here, we demonstrate chemical control of the degree of s-orbital mixing into the spin-bearing d-orbital associated with a series of spin-½ La(II) and Lu(II) molecules. Increased s-orbital character reduces spin-orbit coupling and enhances the electron-nuclear Fermi contact interaction. Both outcomes are beneficial for quantum applications: the former reduces spin-lattice relaxation, while the latter gives rise to a record molecular hyperfine interaction for Lu(II) that, in turn, generates a massive 9 GHz hyperfine clock transition and an order of magnitude increase in phase memory time. These findings suggest new strategies for development of molecular quantum technologies, akin to trapped ion systems.

Electron spin–lattice relaxation of Ni2+

1969 ◽  
Vol 47 (16) ◽  
pp. 1753-1756 ◽  
Author(s):  
K. P. Lee ◽  
D. Walsh
Keyword(s):  
Electron Spin ◽  
Lattice Relaxation ◽  
Magnesium Nitrate ◽  
Spin Lattice Relaxation ◽  
Direct Process ◽  
Effective Spin ◽  
Strongly Coupled ◽  
Spin Lattice ◽  
Phonon Bottleneck ◽  
Spin Triplet

The electron spin–lattice relaxation rate by the direct process for Ni2+ in lanthanum magnesium nitrate is surprisingly fast (5 × 103 s−1 at 1.55 °K). Ni2+ is a non-Kramers ion, however, and consequently is strongly coupled to the lattice in most cases. The effective spin triplet and the absence of both hyperfine structure and phonon bottleneck are optimum requirements for a maser material.

SPIN–LATTICE RELAXATION EFFECTS OBSERVED IN THE CONTINUOUS POWER SATURATION OF PARAMAGNETIC LINES

1960 ◽  
Vol 38 (3) ◽  
pp. 495-503 ◽  
Author(s):  
G. V. Marr ◽  
Prem Swarup
Keyword(s):  
Transition Probability ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Pulse Technique ◽  
Effective Spin ◽  
Spin Lattice ◽  
Relaxation Effects ◽  
Continuous Power ◽  
Photon Interactions

The dependence of the conventional saturation parameter on the incident microwave power is considered for Lorentzian-shaped paramagnetic lines and applied to a study of the [Formula: see text] transitions of Cr+++ in K3Co(CN)6 and Gd+++ in La(C2H5SO4)3∙9H2O at 9 kMc/sec and 4.2 °K. It is shown that the experimental observations may be explained on the basis of a spin–lattice transition probability which depends on spin–photon interactions. Values of the effective spin–lattice relaxation times are compared with pulse technique determinations and estimates of the corresponding phonon relaxation times are also given.

Order fluctuations in p-methoxybenzylidene p-n-butylaniline (MBBA): A proton NMR study

1976 ◽  
Vol 54 (15) ◽  
pp. 1600-1605 ◽  
Author(s):  
Ronald Y. Dong ◽  
E. Tomchuk ◽  
J. J. Visintainer ◽  
E. Bock
Keyword(s):  
Nematic Phase ◽  
Frequency Dispersion ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Hydrodynamic Modes ◽  
Spin Lattice ◽  
Nmr Study ◽  
Order Of Magnitude ◽  
To Come

Proton spin–lattice relaxation has been studied in the nematic phase of MBBA and MBBA-d8 samples. The proton T1 temperature dependence appears to come from the motions of side chains as in p-azoxyanisole. Order of magnitude calculations of T1 based on order fluctuations agree with the ring proton T1. The proton T1 frequency dispersion of MBBA at 18 °C can be explained by order fluctuations plus a frequency dependent B term without any cutoff in the hydrodynamic modes.

Characterization of Amorphous and Crystalline TiCuDx By Deuteron Magnetic Resonance

1986 ◽  
Vol 80 ◽  
Author(s):  
M. P. Volz ◽  
V. P. Bork ◽  
P. A. Fedders ◽  
R. E. Norberg ◽  
R. C. Bowman ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Amorphous Material ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Conduction Electrons ◽  
Spin Lattice ◽  
Order Of Magnitude ◽  
Deuteron Spin

AbstractThe structure and dynamics of a-TiCu(D,H)1.7 and a-TiCu(D,H)1.4 have been examined by Fourier transform quadrupole echo DMR line shape and relaxation time measurements at 30.7 MHz. The quadrupole-broadened a-TiCu(D,H)x line widths narrowed appreciably above 300 K because of increased D mobility. Low temperature DMR spectra show that static quadrupolar broadening is larger for amorphous samples than for crystalline samples. Deuteron spin lattice relaxation is attributed to conduction electrons below 200 K and to quadrupolar interactions at higher temperatures where deuteron hopping becomes significant. The spin lattice relaxation times indicate that the deuteron mobility is larger by an order of magnitude in the amorphous material than in the crystalline counterparts. Results are compared with those from proton magnetic resonance in corresponding hydrides.

THEORY OF THE SPIN-LATTICE INTERACTION IN PARAMAGNETIC SALTS OF IRON-GROUP IONS

1966 ◽  
Vol 44 (7) ◽  
pp. 1613-1630 ◽  
Author(s):  
J. Van Kranendonk ◽  
Y. Y. Lee
Keyword(s):  
Coupling Constants ◽  
Subsequent Paper ◽  
Iron Group ◽  
Spin Variable ◽  
Effective Spin ◽  
General Symmetry ◽  
Spin Lattice ◽  
Lattice Coupling ◽  
Radiation Processes

The form of the spin-lattice coupling in hydrated salts of the iron-group ions is derived in terms of the lattice vibrational coordinates and the effective spin variable, using general symmetry arguments. The most important coupling terms for octahedral and spherical symmetry are given, and the role of the breathing and rotational modes is discussed, as well as the concept of adiabatic and non-adiabatic coupling. This work forms the basis of the semiclassical theory of phonon radiation processes and phonon multipole fields and interactions to be presented in a subsequent paper. Finally, explicit expressions for the coupling constants in terms of the electronic structure of the ions are also derived, for the case of a nondegenerate ground orbital level.

scholarly journals Clock Transition Due to a Record 1240 G Hyperfine Interaction in a Lu(II) Molecular Spin Qubit

2021 ◽  
Author(s):  
Krishnendu Kundu ◽  
Jessica R. K. White ◽  
Samuel A. Moehring ◽  
Jason M. Yu ◽  
Joseph W. Ziller ◽  
...  
Keyword(s):  
Hyperfine Interaction ◽  
Self Assembly ◽  
Scale Up ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Clock Transition ◽  
Spin Lattice ◽  
Memory Time ◽  
Order Of Magnitude ◽  
Orbital Character

Spins in molecules are particularly attractive targets for next-generation quantum technologies, enabling chemically programmable qubits and potential for scale-up via self-assembly. Here, we demonstrate chemical control of the degree of s-orbital mixing into the spin-bearing d-orbital associated with a series of spin-½ La(II) and Lu(II) molecules. Increased s-orbital character reduces spin-orbit coupling and enhances the electron-nuclear Fermi contact interaction. Both outcomes are beneficial for quantum applications: the former reduces spin-lattice relaxation, while the latter gives rise to a record molecular hyperfine interaction for Lu(II) that, in turn, generates a massive 9 GHz hyperfine clock transition and an order of magnitude increase in phase memory time. These findings suggest new strategies for development of molecular quantum technologies, akin to trapped ion systems.

Anisotropy of antiferromagnetic spin fluctuations in the heavy fermion superconductors of CeMIn5 and PuMGa5 (M=Co, Rh)

2010 ◽  
Vol 1264 ◽  
Author(s):  
Hironori Sakai ◽  
Shinsaku Kambe ◽  
Yo Tokunaga ◽  
Yoshinori Haga ◽  
Seung -H. Baek ◽  
...  
Keyword(s):  
Heavy Fermion ◽  
Lattice Relaxation ◽  
Spin Fluctuations ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Spin Lattice ◽  
Fermion Systems ◽  
Heavy Fermion Systems ◽  
Order Of Magnitude ◽  
Antiferromagnetic Spin

AbstractThe anisotropy of antiferromagnetic spin fluctuations has been investigated microscopically in the heavy fermion systems of CeMIn5 and PuMGa5 (M=Co, Rh) by means of nuclear magnetic resonance (NMR). Both systems are known to be relatively high-Tc superconductors among the heavy fermion systems, especially PuCoGa5, which has a Tc=18.5 K almost one order of magnitude larger than for CeCoIn5 ( Tc=2.3 K). Analysis of the Knight shift and spin-lattice relaxation rates suggests XY-type anisotropy in the antiferromagnetic spin fluctuations in the normal states of these unconventional superconductors. Moreover, the 115 superconductors with larger XY-type fluctuations have a higher Tc, compared to the anisotropy of spin fluctuations in the related paramagnetic system UFeGa5 and antiferromagnets UPtGa5, NpCoGa5, NpFeGa5.

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