scholarly journals Power-law Form of the Temperature Dependence of the Magnon Specific Heat CM(T) in Linear, Planar and Spatial Antiferromagnets

1984 ◽  
Vol 37 (3) ◽  
pp. 305 ◽  
Author(s):  
SJ Joshua
Keyword(s):  
Low Temperature ◽  
Specific Heat ◽  
Temperature Dependence ◽  
Spin Wave ◽  
Power Law ◽  
Power Laws ◽  
Wave Approximation ◽  
Simple Power ◽  
Low Dimensionality

The power-law form of the temperature dependence of the magnon specific heat has been calculated for some real, low dimensionality antiferromagnetic crystals. The simple power laws predicted from dimensionality considerations are reproduced in the low temperature, non-interacting spin-wave approximation, but with limited validity.

Modified spin-wave theory applied to one-dimensional Heisenberg ferromagnet with the nearest-neighbor and next-nearest-neighbor exchange anisotropies

2019 ◽  
Vol 33 (11) ◽  
pp. 1950106
Author(s):  
Yun Liao ◽  
Yuan Chen ◽  
Ji Pei Chen ◽  
Wen An Li
Keyword(s):  
Low Temperature ◽  
Specific Heat ◽  
Spin Wave ◽  
Nearest Neighbor ◽  
Wave Theory ◽  
Heisenberg Ferromagnet ◽  
Thermodynamic Quantities ◽  
One Dimensional ◽  
Spin Wave Theory ◽  
The One

The modified spin-wave theory is used to investigate the one-dimensional Heisenberg ferromagnet with the nearest-neighbor (NN) and next-nearest-neighbor (NNN) exchange anisotropies. The ground-state and low-temperature properties of the system are studied within the self-consistent method. It is found that the effect of the NN anisotropy on the thermodynamic quantities is stronger than that of the NNN anisotropy in the low-temperature region. The anisotropy dependence behaviors (such as the power, exponential and linear laws) are obtained for the position and the height of the maximum of the specific heat and its coefficient, as well as the susceptibility coefficient. The specific heat and its coefficient both display the low-temperature double maxima which are induced by the anisotropies and the NNN interaction. In the very low temperatures the specific heat and the susceptibility behave severally as T[Formula: see text] and T[Formula: see text] at the critical point J2/J1 = −0.25, where J1 and J2 are the NN and NNN interactions, respectively.

SPIN FLUCTUATIONS IN TCo2 STUDIED BY RESISTIVITY AND THERMOPOWER EXPERIMENTS (T = Y, Lu, Sc, Hf, Zr, Ce)

1993 ◽  
Vol 07 (01n03) ◽  
pp. 370-373 ◽  
Author(s):  
N. BARANOV ◽  
E. BAUER ◽  
E. GRATZ ◽  
R. HAUSER ◽  
A. MARKOSYAN ◽  
...  
Keyword(s):  
Low Temperature ◽  
Specific Heat ◽  
Temperature Dependence ◽  
Temperature Region ◽  
Low Temperatures ◽  
Spin Fluctuations ◽  
General Tendency ◽  
Electronic Specific Heat ◽  
Temperature Dependent

The temperature dependence of the resistivity and the thermopower in the region from 4.2K up to 1000K for the six isostructural paramagnetic compounds TCo 2 (T=Y, Lu, Sc, Hf, Zr, Ce) is studied. The resistivity ρ (T) follows a T 2 dependence at low temperatures in all these compounds. Plotting the A values into an A vs. γ2 diagram shows that YCo 2, LuCo 2, and ScCo 2 are spinfluctuation systems (A and γ denote the coefficients in ρ (T) = ρ0 + AT 2 and that of the electronic specific heat, respectively) HfCo 2 and ZrCo 2 do not fit into this general tendency in the ( A , γ2)-diagram. The temperature dependent thermopower S(T) in YCo 2, LuCo 2 and ScCo 2 exhibits a pronounced minimum in the low temperature region. These minima are obviously connected with the existence of spin fluctuations (paramagnon-drag). Spin fluctuations in HfCo 2 and ZrCo 2 are less important. This we conclude also from the ten times smaller A-values and the missing minimum in the thermopower at low temperatures.

The low temperature specific heats of some pure metals (Cu, Ag, Pt, Al, Ni, Fe, Co)

1965 ◽  
Vol 285 (1403) ◽  
pp. 561-580 ◽  
Keyword(s):  
Boundary Layer ◽  
Low Temperature ◽  
Specific Heat ◽  
Spin Wave ◽  
Vapour Pressure ◽  
Effective Field ◽  
Weighting Schemes ◽  
Specific Heats ◽  
Nuclear Contribution ◽  
Pure Metals

Details are given of the construction of a calorimeter to operate in the range 1.2 to 4.2 °K. Analyses of the results obtained for several pure metals (Cu, Ag, Pt, Al, Ni, Fe, Co) are given for various weighting schemes in reducing the results. The effects of errors due to the possible presence of a Kapitza boundary layer affecting the temperatures deduced from vapour pressure bulb measurements are considered. The results are analysed with a view to detecting further lattice contributions to the specific heat ( T 5 terms) and (in the case of ferromagnetics) spin wave contributions. The nuclear contribution and the effective field is evaluated for cobalt.

Influence of next-nearest neighbor interaction on low temperature properties of the spin-1/2 one-dimensional ferromagnetic XY model

2015 ◽  
Vol 29 (31) ◽  
pp. 1550225 ◽  
Author(s):  
Songqiu Yin ◽  
Yuan Chen
Keyword(s):  
Low Temperature ◽  
Specific Heat ◽  
Spin Wave ◽  
Nearest Neighbor ◽  
Wave Theory ◽  
Xy Model ◽  
Neighbor Interaction ◽  
One Dimensional ◽  
Spin Wave Theory ◽  
The One

In this paper, we apply spin-wave theory to the one-dimensional spin-1/2 ferromagnetic XY model with the next-nearest neighbor interaction. The thermodynamic divergences which the conventional spin-wave theory encounters with, are solved by implementing Takahashi’s idea through introducing a Lagrange multiplier in the Hamiltonian to keep zero magnetization. It is shown that the next-nearest neighbor interaction has an influence on the ground-state and low temperature properties of the system. The exponential laws which are induced by the next-nearest neighbor interaction, are found for heights of maxima of the specific heat and its coefficient, as well as the maximum and minimum of the susceptibility coefficient. The maximum positions of the specific heat and its coefficient fit well to the linear and exponential laws under the next-nearest neighbor interaction, respectively.

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