Calculation of the thermal conductivity and the specific heat of the lattice for a spin-boson system at low temperatures

1992 ◽  
Vol 88 (2) ◽  
pp. 215-222
Author(s):  
W. Schiller
1987 ◽  
Vol 26 (S3-2) ◽  
pp. 1217 ◽  
Author(s):  
H. R. Ott ◽  
E. Felder ◽  
A Bernasconi ◽  
Z. Fisk ◽  
J. L. Smith ◽  
...  

An apparatus is described in which the thermal conductivity of solids can be determined at any temperature between 2 and 90°K. Several glasses and dielectric crystals have been measured. It had previously been found that at high temperatures the conductivity of glasses is proportional to the specific heat, but at low temperatures it falls off more slowly than the specific heat. The present experiments show that there is a temperature region in which the conductivity is nearly independent of temperature. A similar variation of conductivity is found for the thermo-plastic Perspex. The effect of lattice defects in crystals was studied by measuring the thermal conductivity of a quartz crystal before and after successive periods of neutron irradiation. After prolonged irradiation the conductivity approached, in both magnitude and temperature variation, that of quartz glass. Subsequent heating produced a substantial recovery in the conductivity. The results on both glasses and on crystals can be explained by the theory developed by Klemens (1951). Further measurements made on a corundum crystal confirm the importance of the ‘Umklapp’ processes, postulated by Peierls, in causing thermal resistance.


1953 ◽  
Vol 6 (4) ◽  
pp. 405 ◽  
Author(s):  
PG Klemens

The specific heat of graphite is discussed in terms of a modified Debye treatment. It is shown that the contribution from the longitudinal waves varies as T3 below 45 �K, and as T2 at higher temperatures, whereas the usual two-dimensional treatment leads to a T2 variation at all low temperatures. Similarly the transverse contribution varies as T3 at lowest temperatures, But above 10 �K it varies as T2.


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