Frustrated exchange interactions formation at low temperatures and high hydrostatic pressures in La0.70Sr0.30MnO2.85

The magnetic and thermal properties of the anion-deficient La0.70Sr0.30MnO2.85 manganite are investigated in wide temperature (4-350 K) range, including under hydrostatic pressure (0-1.1 GPa). Throughout the pressure range investigated, the sample is spin glass with diffused phase transition into paramagnetic state. It is established, that spin glass state is a consequence of exchange interaction frustration of the ferromagnetic clusters embeded into antiferromagnetic clusters. The magnetic moment freezing temperature T (f) of ferromagnetic clusters increases under pressure, freezing temperature dependence on pressure is characterized by derivative value similar to 4.5 K/GPa, while the magnetic ordering T (MO) temperature dependence is characterized by derivative value similar to 13 K/GPa. The volume fraction of sample having ferromagnetic state is V (fer) similar to 13% and it increases under a pressure of 1.1 GPa by Delta V (fer) a parts per thousand 6%. Intensification of ferromagnetic properties of the anion-deficient La0.70Sr0.30MnO2.85 manganite under hydrostatic pressure is a consequence of oxygen vacancies redistribution and unit cell parameters decrease. The most likely mechanism of frustrated exchange interactions formation is discussed.