Premium
Thermal Conductivity of Rare‐Earth Orthoferrites at Reorientation Phase Transitions
Author(s) -
Barilo S. N.,
Ges A. P.,
Soshnikov L. E.,
Smirnova T. V.
Publication year - 1984
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221220105
Subject(s) - orthoferrite , condensed matter physics , anisotropy , materials science , phonon , thermal conductivity , phase (matter) , mean free path , magnetization , chemistry , physics , magnetic field , optics , organic chemistry , quantum mechanics , scattering , composite material
The dependence of thermal conductivity on temperature is measured for the first time for three compositions of rare‐earth orthoferrites (REO): SmFeO 3 , Sm 0.4 Gd 0.4 FeO 3 , and Sm 0.65 Er 0.15 Tb 0.2 · ·FeO 3 in the spin reorientation region (SRR). Characteristic anomalies are found on curves λ( T ) at temperatures of reorientation phase transitions. Presence and form of the anomalies are associated with the summary effect of the changes of the specific heat, averaged free‐path length of phonons, and their averaged velocity of propagation. The behaviour of the averaged velocity of the phonon propagation at magnetic phase transitions is studied on the basis of the temperature dependence of the velocity of the shear sound wave. An interpretation is given by using the phenomenological model conformably to the case of REO. The values of the four‐fold anisotropy K b = 7.97 × 10 3 J/m 3 and magnetoelastic coupling B 55 = 4.472 × 10 6 J/m 3 constants are estimated for the compound Sm 0.6 Gd 0.4 FeO 3 . The temperature dependence of two‐fold anisotropy constant K u ( T ) in the spin‐reorientation region and its ranges are calculated by way of example of a samarium–gadolinium orthoferrite.