Field- and pressure-induced phases in Sr4Ru3O10: a spectroscopic investigation.

We have investigated the magnetic-field- and pressure-induced structural and magnetic phases of the triple-layer ruthenate Sr4Ru3O10. Magnetic-field-induced changes in the phonon spectra reveal dramatic spin-reorientation transitions and strong magnetoelastic coupling in this material. Further, we are able to deduce key magnetoelastic coupling parameters, and evidence that the magnetic moments are localized on the Ru sites. Additionally, pressure-dependent Raman measurements at different temperatures reveal an anomalous negative Gruneisen parameter associated with the B(1g) mode (approximately 380 cm(-1)) at low temperatures (T < 75 K), which can be explained consistently with the field-dependent Raman data.