Huang Zixin, Avdeev Maxim, Kennedy Brendan J, Knight Kevin S, Zhou Qingdi, Ling Chris D
School of Chemistry, The University of Sydney, Sydney 2006, Australia.
J Phys Condens Matter. 2014 Jul 9;26(27):276003. doi: 10.1088/0953-8984/26/27/276003. Epub 2014 Jun 17.
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.
我们通过实验研究了压力对与Ba3BiIr2O9和Ba3BiRu2O9中自旋能隙打开相关的磁弹性转变的影响。对于这两种化合物，发现通过外部物理压力和内部化学压力减小晶胞体积会降低转变温度T()，并且在较小程度上降低相关负热体积膨胀的幅度。结果得出了与转变相关的潜热，Ba3BiIr2O9为 -3.34(3)×10(2) J mol(-1)，Ba3BiRu2O9为 -7.1(5)×10(2) J mol(-1)。Ba3BiRu2O9中的转变比Ba3BiIr2O9中的转变明显更稳定，需要高一个数量级的压力才能实现相同程度的T()降低。这两种化合物的不同响应表明4d和5d金属之间存在差异，因此也表明自旋轨道耦合的重要性，预计Ir化合物中的自旋轨道耦合要强得多。
