Ultrasonic Measurement of LaCoO3 —Evidence for the Orbital-Order Fluctuation—
Ultrasonic Measurement of LaCoO3 —Evidence for the Orbital-Order Fluctuation—
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LaCoO3 的超声波测量 —轨道级数涨落的证据 —
DOI：
10.1143/jpsj.75.084601
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发表时间：
2006
影响因子：
1.7
通讯作者：
K. Asai
中科院分区：
文献类型：
--
作者：
T. Naing;Toshi;Y. Kobayashi;Masaru Suzuki;K. Asai
在4 ~ 580 K温度范围内，测量了频率f为10 ~ 100 MHz的纵向（L）和横向（T）声波在LaCoO 3 [111]上沿着传播的声速。单畴菱面体晶体的数据与孪生伪立方试样的数据的比较揭示了菱面体对称性的弹性常数的各向异性。的L模式与f =10 MHz的速度的温度依赖性分析一致的反常晶格膨胀与自旋态转变。在100 K以上，L模出现声速频散.色散的幅度随着温度的升高而显著增加，直到测量的最高温度。用德拜模型计算的弛豫速率为激活型，弛豫频率为（1/τ）0 =187× 106 s-1，弛豫能量为11 meV.缓慢的晶格弛豫是由于一个波动的…
The sound velocity propagating along [111] of LaCoO 3 has been measured from 4 to 580 K for longitudinal ( L ) and transverse ( T ) sounds with frequencies, f , of 10 to 100 MHz. A comparison of the data for the single-domain rhombohedral crystal with those for a twinned pseudocubic specimen reveals the anisotropy of the elastic constants with the rhombohedral symmetry. The temperature dependence of the velocity of the L mode with f =10 MHz is analyzed consistently with the anomalous lattice expansion associated with the spin state transition. A frequency dispersion of the sound velocity appears in the L mode above 100 K. The amplitude of the dispersion increases pronouncedly with increasing temperature up to the measured highest temperature. The relaxation rate of the lattice evaluated based on the Debye model shows an activation type of temperature dependence with an attempt frequency of (1/τ) 0 =187×10 6 s -1 and the energy E a =11 meV. The slow lattice relaxation is attributed to a fluctuation of the ...