Gorodilov B. Impurity effects in low temperature thermal conductivity of cryocrystals

The object of the study are thermal conductivity of pure and dopped quantum and clasic crystals. The method of research is the steady state measurement method a coefficient thermal conductivity of cryocrystals in temperatures range 1.5 - 20 K. The influence normal phonon-phonon processes scattering have observed on thermal conductivity solid hydrogens. The possibility of united description normal phonon-phonon processes has been motivated experimental for classical and quantum crystals. At the first time anomalous influence the quasiisotopic impurity (neon) at concentrations of order 1 ppm on the thermal conductivity solid parahydrogen with the concentration dependent of the thermal resistence weaker than line has been observed. Observed effect quantitatively and qualitatively have been explained by interference resistivity and normal phonon-phonon processes scattering. The contribution of quantum effects in the isotopic impurity phonon scattering has been detached in the hard hydrogen. At the first time the new mechanism of nonisotopic impurity phonon scattering has been observed (argon in parahydrogen). A influence of rotation motion of impurity molecules on the thermal conductivity of classical and quantum crystals has been studied experimentally. It has shown that in all cases impurity phonon scattering has a resonance nature.