Pressure Dependence of the Magnetic Transitions in Dysprosium and Erbium
Pressure Dependence of the Magnetic Transitions in Dysprosium and Erbium
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镝和铒磁转变的压力依赖性
DOI：
10.1103/physrev.160.387
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发表时间：
1967
期刊：
影响因子：
--
通讯作者：
T. Scott
中科院分区：
文献类型：
--
作者：
J. Milton;T. Scott
本文研究了在7千巴压力下流体静压对镝、铒多晶样品磁转变的影响。使用氦气系统产生压力，并通过用精密比率变压器电桥测量包含样品的线圈的自感来检测转变。对于镝的反铁磁相变，我们发现dTNdP的大小随压力的增加而增加，初始值为-0.44 ± 0.02K/kbar，平均值约为-0.5K/kbar。铒的奈耳跃迁的斜率为-0.26 ±0.01 K/kbar。铁磁转变的测定因镝的加热和冷却数据之间的滞后效应和铒的电感随温度的相当复杂的变化而变得复杂;但通过系统的实验程序，包括在宽范围内的温度循环和缓慢的温度变化率，人们相信获得了居里转变的压力依赖性的可靠值。对于镝，在大气压下电感-温度曲线的拐点与文献中的转变温度值相吻合，因此也被用来表示在高压下的转变，得到d T c dP=− 1.24±0.10 K/kbar。对于铒，在4.2和60 K之间，在冷却曲线上观察到两个峰，在升温曲线上观察到三个峰。升温的低温峰与报道的20 K的居里转变相吻合，并发现其压力依赖性为-0.8 ±0.2 K/kbar。一个高温峰值与升温曲线上的53.5 K峰值相吻合，该峰值已在比热和磁测量中报道，并且还与中子衍射实验中在52 K处报道的磁化横向于c轴变化的转变相关联。该峰显示出-1.3 ±0.2 K/kbar的压力依赖性。在约25 K冷却时观察到的强峰与压力无关，但在升温曲线上，位于稍高的温度，并与压力有关。结果进行了比较，与其他测量的稀土，并与理论。
The effect of hydrostatic pressure on the magnetic transitions of polycrystalline samples of dysprosium and erbium has been studied to 7 kbar. Pressure was generated using a helium-gas system and the transitions were detected by measuring, with a precision ratio-transformer bridge, the self-inductance of a coil containing the samples. For the antiferromagnetic transition of dysprosium we find that d T N dP increases in magnitude with pressure, having an initial value of-0.44±0.02 K/kbar and an average of about-0.5 K/kbar. The Néel transition of erbium shows a constant slope of-0.26±0.01 K/kbar. Determination of the ferromagnetic transitions was complicated by a hysteresis effect between warming and cooling data for dysprosium and a rather complicated variation of inductance with temperature for erbium; but with the exercise of systematic experimental procedure, including temperature cycling over a wide range and slow rates of temperature change, it is believed that reliable values for the pressure dependence of the Curie transition were obtained. For dysprosium, an inflection point in the inductance-temperature curve coincided at atmospheric pressure with the reported value of the transition temperature and was taken, therefore, to indicate the transition under high pressure as well, yielding d T c dP=− 1.24±0.10 K/kbar. For erbium, between 4.2 and 60 K, two peaks were observed on cooling curves and three on warming curves. The low-temperature peak on warming coincided with the reported Curie transition at 20 K and was found to have a pressure dependence of-0.8±0.2 K/kbar. A high-temperature peak coincided on warming curves with a 53.5 K peak that has been reported in specific-heat and magnetic measurements and is also associated with a transition reported at 52 K from neutron-diffraction experiments in which the magnetization transverse to the c axis changes. This peak shows a pressure dependence of-1.3±0.2 K/kbar. A strong peak observed at about 25 K on cooling was pressure-independent, but on warming curves, was located at a slightly higher temperature and was pressure-dependent. The results are compared with other measurements on the rare earths, and with theory.