title: Tuning the giant magnetoelastic transition in Ba3BiIr2O9 and Ba3BiRu2O9.
abstract: We have experimentally investigated the effects of pressure on the magnetoelastic transitions associated with the opening of spin-gaps in Ba3BiIr2O9 and Ba3BiRu2O9. For both compounds, reducing the unit cell volume by either external physical and internal chemical pressure was found to reduce the temperature T(*) of the transition and, to a lesser extent, the magnitude of the associated negative thermal volume expansion. The results yield the latent heat associated with the transitions, -3.34(3) × 10(2) J mol(-1) for Ba3BiIr2O9 and -7.1(5) × 10(2) J mol(-1) for Ba3BiRu2O9. The transition in Ba3BiRu2O9 is significantly more robust than in Ba3BiIr2O9, requiring an order of magnitude higher pressures to achieve the same reduction in T(*). The differing responses of the two compounds points to differences between the 4d and 5d metals and hence to the importance of spin-orbit coupling, which is expected to be much stronger in the Ir compound.
authors.affiliation: School of Chemistry, The University of Sydney, Sydney 2006, Australia.
authors.forename: Zixin
authors.initials: Z
authors.lastname: Huang
authors.forename: Maxim
authors.initials: M
authors.lastname: Avdeev
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Kennedy
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Knight
authors.forename: Qingdi
authors.initials: Q
authors.lastname: Zhou
authors.forename: Chris D
authors.initials: CD
authors.lastname: Ling
mesh_terms: D017609:Barium Compounds / Q000737:chemistry*; D003198:Computer Simulation; D055119:Elastic Modulus; D004735:Energy Transfer; D060526:Magnetic Fields; D008422:Materials Testing; D008956:Models, Chemical; D044367:Phase Transition; D011312:Pressure; D013113:Spin Labels; D013696:Temperature
chemical_list: D017609:Barium Compounds; D013113:Spin Labels