Formation of a glassy phase in solid⁴He. Contribution to the pressure in the supersolidlty region

High-precision pressure measurements in solid ⁴He, grown by the capillary blocking technique, have been made in a temperature range from 50 to 800 mK on crystals of different quality, both fresh-grown and well-annealed. In unannealed crystals, the temperature dependence of pressure demonstrates a contribution proportional to T², which dominates at temperatures T < 300 mK, where an abnormal behavior attributed to « supersolidity» has been previously observed. Such a pressure behavior is specific to glassy phase. The contribution of a glassy phase was not observed practically in well-annealed samples. The effect observed testifies that the glassy phase is formed rather easily in solid helium with a high concentration of nonequilibrium defects. An abnormally drastic pressure relaxation in poor-quality samples was registered at temperatures close to the melting point. Possible reasons for this effect are discussed.