Description of ordering, temperature dependence of susceptibility, and magnetostriction of a one-sublattice spin system with S=1 and strong biquadratic exchange

1998 ◽  
Vol 24 (10) ◽  
pp. 721-725 ◽  
Author(s):  
V. M. Kalita ◽  
A. F. Lozenko
Keyword(s):  
Temperature Dependence ◽  
Spin System ◽  
Biquadratic Exchange

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.

ESR STUDIES OF GMR RELATED MATERIALS I: ESR of Mn IN LaMnO3 AND La0.99Ca0.01MnO3

2000 ◽  
Vol 14 (25n26) ◽  
pp. 883-897 ◽  
Author(s):  
N. ARAI ◽  
K. SUGAWARA
Keyword(s):  
Magnetic Susceptibility ◽  
Temperature Dependence ◽  
Spin System ◽  
High Field ◽  
Energy Gap ◽  
Low Field ◽  
High Field Esr ◽  
Clear Signal ◽  
Spin Clusters ◽  
G Value

ESR measurements are carried out for La 1-x Ca x MnO 3 (x=0, 0.01) from 760 K down to 4 K. A clear signal was observed above 260 K, presumably arising from Mn 3+ and Mn 4+, but two kinds of signals, the low-field and high-field ESR with g≃2, were observed below it. The high- and low-field signals are tentatively assumed to originate from Mn 4+ and Mn 3+, respectively. The g-value, linewidth, and intensity of the high-field signal nearly follow ∝1/(T-106). The temperature dependence of g-shift of the low-field signal is similar to that of magnetic susceptibility of LaMnO 3. The ESR intensity anomalously increases at temperatures between about 150 K and 250 K, which is tentatively ascribed to the occurrence of "spin-clusters". Above ≃300 K, the ESR intensity nearly follows Curie's law, and the linewidth is proportional to exp (-500/T), an indication of some kind of energy-gap existence in the Mn spin system.

ZERO FIELD ENTANGLEMENT IN DIPOLAR COUPLING SPIN SYSTEM AT NEGATIVE TEMPERATURE

2013 ◽  
Vol 11 (05) ◽  
pp. 1350050 ◽  
Author(s):  
GREGORY B. FURMAN ◽  
VICTOR M. MEEROVICH ◽  
VLADIMIR L. SOKOLOVSKY
Keyword(s):  
Magnetic Field ◽  
Temperature Dependence ◽  
Spin System ◽  
Dipolar Coupling ◽  
Negative Temperature ◽  
Absolute Temperature ◽  
Zero Magnetic Field ◽  
Entangled States ◽  
Zero Field ◽  
Negative Temperatures

A dipolar coupled spin system can achieve internal thermodynamic equilibrium states at negative absolute temperature. We study analytically and numerically the temperature dependence of the concurrence in a dipolar coupled spin-1/2 system in both nonzero and zero fields and show that, at negative temperatures, entangled states can exist even in zero magnetic field.

Biquadratic Exchange in a Two-Spin System

1989 ◽  
Vol 153 (1) ◽  
pp. K73-K77 ◽  
Author(s):  
J. L. Cadorin ◽  
W. Figueiredo
Keyword(s):  
Spin System ◽  
Biquadratic Exchange
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