MAGNETIC-STRUCTURES OF CUBIC FEGE STUDIED BY SMALL-ANGLE NEUTRON-SCATTERING
MAGNETIC-STRUCTURES OF CUBIC FEGE STUDIED BY SMALL-ANGLE NEUTRON-SCATTERING
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DOI：
10.1088/0953-8984/1/35/010
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发表时间：
1989-09-04
影响因子：
2.7
通讯作者：
FRELTOFT, T
中科院分区：
文献类型：
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作者：
LEBECH, B;BERNHARD, J;FRELTOFT, T
用小角中子散射法研究了立方多晶型FeGe单晶的磁有序。该化合物在TN=278.7 K时按磁性有序排列成长程螺旋(周期约683-700AA)，在高温下沿当量方向传播，在低温时沿当量方向传播。螺旋波矢的长度几乎与温度无关。T_N处的相变为一级相变，磁滞很小。螺旋方向转向的过渡相当缓慢。它发生在大约40K的温度间隔内，并显示出明显的温度滞后(T2向下箭头=211K，T2向上箭头=245K)。根据温度和磁场方向的不同，20-40mT的外加磁场会使螺旋轴转向外加磁场的方向。随着磁场的进一步增加，反铁磁螺旋的幅度减小，而铁磁成分增加，直到在大约200-300mT以上的磁场下，立方FeGe变得磁饱和。立方FeGe中的磁有序是Dzyaloshinskii螺旋，类似于等结构化合物MnSi中观察到的结构。然而，在MNSI中，螺线在低于TN=29.5K的所有温度下都沿着等效的<；111>；方向传播。
The magnetic ordering of a single crystal of the cubic polymorph of FeGe has been studied by small-angle neutron scattering. The compound orders magnetically at T N= 278.7 K into a long-range spiral (period approximately 683-700 AA) propagating along equivalent< 100> directions at high temperatures and along equivalent< 111> directions at low temperatures. The length of the spiral wavevector is nearly independent of temperature. The transition at T N is first order with very little hysteresis. The transition at which the direction of the spiral turns is rather sluggish. It takes place in a temperature interval of approximately 40 K and shows pronounced temperature hysteresis (T 2 down arrow= 211 K, T 2 up arrow= 245 K). Applied magnetic fields of 20-40 mT, depending on the temperature and the field direction, cause the spiral axis to turn into the direction of the applied field. As the field is further increased, the amplitude of the antiferromagnetic spiral decreases and the ferromagnetic component increases until at fields above approximately 200-300 mT cubic FeGe becomes magnetically saturated. The magnetic ordering in cubic FeGe is a Dzyaloshinskii spiral similar to the structure observed in the isostructural compound MnSi. However, in MnSi the spiral propagates along equivalent< 111> directions at all temperatures below T N= 29.5 K.