NEUTRON-SCATTERING STUDIES OF THE ANOMALOUS MAGNETIC ALLOY FE0.7AL0.3
NEUTRON-SCATTERING STUDIES OF THE ANOMALOUS MAGNETIC ALLOY FE0.7AL0.3
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DOI：
10.1103/physrevb.28.6183
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发表时间：
1983-01-01
影响因子：
3.7
通讯作者：
MURAOKA, Y
中科院分区：
文献类型：
--
作者：
MOTOYA, K;SHAPIRO, SM;MURAOKA, Y
小角总中子散射和非弹性中子散射测量进行了有序合金Fe 0.7 Al 0.3的单晶。小角强度的Q依赖性行为可以分为四个温度区，对应于体行为：（i）T> Tc = 510 K（顺磁区）;当T> Tc时，线的形状是洛伦兹的，κ→ 0。(ii)300 K< T<Tc（铁磁区）; I（Q）<$Q− 2，正如自旋波所预期的。(iii)100 K< T< 300 K（接近Tc inv）; I（Q）<$Q− α，α与T有关，最大值α= 2.6。在该区域中，强度的T依赖性表现出依赖于Q的峰。在Tc inv = 160 K附近，观察到了热滞后和新的散射时间依赖性. (iv)T< 100 K（自旋玻璃区）;线的形状也是洛伦兹的，κ随着T的降低而增加。在T_f = 90 K时未观察到反常现象。非弹性测量表明，自旋波存在于铁磁区，但随着温度的降低而消失。当温度低于Tc inv时，出现一个弹性中心峰，它随T的降低而增大。结果被解释在随机场效应。
Small-angle total and inelastic neutron scattering measurements were performed on a single crystal of the ordered alloy Fe 0.7 Al 0.3. The behavior of the Q dependence of the small-angle intensity can be classified into four temperature regions which correspond to the bulk behavior:(i) T> T c= 510 K (paramagnetic region); the line shape is Lorentzian with κ→ 0 as T> T c.(ii) 300 K< T< T c (ferromagnetic region); I (Q)∼ Q− 2 as expected from spin waves.(iii) 100 K< T< 300 K (near T c inv); I (Q)∼ Q− α, with α being T dependent and reaching a maximum value α= 2.6. In this region the T dependence of the intensity exhibits a peak which is Q dependent. Near T c inv≈ 160 K, a thermal hysteresis and novel time dependence of the scattering is observed.(iv) T< 100 K (spin-glass regime); the line shape is again Lorentzian with κ increasing with decreasing T. No anomaly is observed at T f≈ 90 K. The inelastic measurements reveal that spin waves exist in the ferromagnetic regime but disappear as the temperature is lowered. For temperatures less than T c inv, an elastic central peak appears which increases as T is decreased. The results are interpreted in terms of random-field effects.