Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK.
J Phys Condens Matter. 2014 Jan 29;26(4):045901. doi: 10.1088/0953-8984/26/4/045901. Epub 2014 Jan 6.
Resonant ultrasound spectroscopy has been used to measure the elastic and anelastic behaviour through known structural and magnetic phase transitions in single crystal hexagonal YMnO3. Anomalous elastic behaviour is observed at the high temperature structural transition at ∼1260 K, with a discontinuity in the elastic constants and nonlinear recovery below Tc, consistent with [Formula: see text] coupling. There is no change in dissipation associated with this high temperature transition, and no evidence in the elastic or anelastic behaviour for any secondary transition at ∼920 K, thus supporting the thesis of a single high temperature transformation. Elastic stiffening is observed on cooling through TN, in accordance with previous studies, and the excess elastic constant appears to scale with the square of the magnetic order parameter. The strains incurred at TN are a factor of ∼20 smaller than those at the structural transition, implying very weak [Formula: see text] coupling and a dominant contribution to the variation in the elastic constants from [Formula: see text]. The increased acoustic dissipation above TN is consistent with an order-disorder process.
共振超声光谱已被用于通过在单晶六方 YMnO3 中已知的结构和磁相变来测量弹性和非弹性行为。在约 1260 K 的高温结构相变处观察到反常弹性行为，弹性常数在 Tc 以下出现不连续和非线性恢复，与[公式：请参见文本]耦合一致。与这个高温转变相关的耗散没有变化，并且在弹性或非弹性行为中没有证据表明在约 920 K 处存在任何次级转变，因此支持单一高温转变的论点。在通过 TN 冷却时观察到弹性变硬，与以前的研究一致，并且过量弹性常数似乎与磁有序参数的平方成正比。在 TN 处产生的应变比在结构转变处的应变小约 20 倍，这意味着[公式：请参见文本]耦合非常弱，并且对弹性常数变化的主要贡献来自[公式：请参见文本]。在 TN 以上的增加的声耗散与有序无序过程一致。
