Pressure effects on magnetic and structural properties of pure and substituted SrRuO3

An influence of hydrostatic pressure on phase transition temperature T-C, spontaneous magnetization M-0, coercive field H-C, and remanent magnetization M-R, has been investigated for the parent perovskite SrRuO3 and substituted ruthenates with decreased (La0.2Sr0.8RuO3, SrRu0.9Mn0.1O3) and increased (SrRu0.9Cr0.1O3) Curie temperature. We have observed a decrease of TC with pressure for all of the studied samples, however, the lowering of T-C with pressure (dT(C)/ dP) is not correlated with the value of T-C at ambient pressure. The spontaneous magnetization and coercive field remain unchanged for most of the samples, except the La0.2Sr0.8RuO3 sample, where spontaneous magnetization decreases with increasing pressure. For SrRuO3, structural study by neutron powder diffraction shows clear contraction of the Ru-O bond lengths under external pressure whereas bond angles and the orthorhombic distortion remain constant at 295 and 50 K. The weakening of the ferromagnetic interactions with increasing pressure is consistent with complex band structure effects through a combination of modulation of the hybridization caused by contraction of the Ru-O bonds and with the significant role of the direct Ru-Ru interactions.