Critical behavior of the Mott transition in Cr-doped V2O3
Critical behavior of the Mott transition in Cr-doped V2O3
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DOI：
10.1103/physrevb.2.3751
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发表时间：
1970-11-01
期刊：
影响因子：
--
通讯作者：
Dernier, P. D.
中科院分区：
文献类型：
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作者：
Jayaraman, A.;McWhan, D. B.;Dernier, P. D.
在298 ° K以上的温度下，通过测量电阻随压力的变化关系，研究了Cr掺杂V2 O3的金属-绝缘体（M-I）转变，该转变已被证明是Mott转变。研究结果表明，M-I相界终止于P-T平面的临界点，与先前的预测一致。在298 K时约为两个数量级的过渡处的不连续电阻下降随着温度逐渐减小，并且超过某一临界温度（取决于Cr浓度）完全消失。在临界温度以上，只能看到电阻的平滑但有点反常的变化。（V1-xCrx）（2）O-3（x = 0.0375、x = 0.0187和x = 0.0135）的临界压力和温度分别为12.5 kbar、390 ° K、5.5 kbar、433 ° K和3.5 kbar、443 ° K。这些数据的直线外推得到纯V2 O3的P-c = -1.5 x 0.2 kbar和T-c =（474 +/- 5）度K。纯V2 O3在500-600度K附近的高温电阻异常是由于超临界行为。在大气压下对x = 0.0137至x = 0.004的Cr掺杂样品的X射线研究表明，与M-I转变相关的AV随着温度的升高而减小，并最终在x = 0.005附近消失。该行为完全类似于已知终止于临界点的γ-至α-Ce相边界。事实上，在Cr掺杂的V2 O3和γ-α-Ce过渡的M-I过渡有许多相似之处，这些进行了讨论。
The metal-insulator (M-I) transition in Cr-doped V2O3, which has been shown to be a Mott transition, was investigated by following the resistance as a function of pressure at temperatures above 298 degrees K. This study has shown that the M-\I phase boundary terminates at a critical point in the P-T plane, in accordance with the earlier prediction. The discontinuous resistance drop at the transition, which is about two orders of magnitude at 298 degrees K, progressively diminishes with temperature and beyond a certain critical temperature, depending upon the Cr concentration, vanishes altogether. Above the critical temperature only a smooth but somewhat anomalous change in resistance is seen. The critical pressure and temperature for (V1-xCrx)(2)O-3 with x = 0.0375, x = 0.0187, and x = 0.0135 were determined as 12.5 kbar, 390 degrees K; 5.5 kbar, 433 degrees K; and 3.5 kbar, 443 degrees K, respectively. A straight-line extrapolation of these data yields P-c = -1.5 x 0.2 kbar and T-c = (474 +/- 5)degrees K for pure V2O3. The high-temperature resistance anomaly in pure V2O3 near 500-600 degrees K is due to supercritical behavior. X-ray studies at atmospheric pressure on Cr-doped samples with x = 0.0137 to x = 0.004 show that the AV associated with the M-I transition decreases with increasing temperature and finally vanishes near about x = 0.005. The behavior is exactly analogous to the gamma- to alpha-Ce phase boundary which is known to terminate at a critical point. Indeed the M-I transition in Cr-doped V2O3 and the gamma- to alpha-Ce transition have many similarities, and these are discussed.