Field-induced reorientation of the spin helix in MnSi near Tc
Field-induced reorientation of the spin helix in MnSi near Tc
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DOI：
10.1103/physrevb.73.224440
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发表时间：
2006-06-01
影响因子：
3.7
通讯作者：
Eckerlebe, H
中科院分区：
文献类型：
--
作者：
Grigoriev, SV;Maleyev, SV;Eckerlebe, H
用小角极化中子散射方法研究了MnSi单晶在外场作用下的手征自旋涨落和螺旋结构。沿其中一个轴沿着施加弱磁场< 111 >，产生螺旋波矢量沿着磁场的单畴样品。在130 ~ 180 mT的磁场范围内，在T-c附近观察到自旋螺旋从[111]轴到[110]轴的90度重取向。进一步增加的字段以上180 mT恢复的螺旋线的原始取向，并导致在350 mT的感应铁磁状态。这一观察结果澄清了用其他技术在MnSi的H-T相图中发现的结构自旋不稳定性的性质。我们解释了这种现象的立方各向异性的竞争和自旋波玻色凝聚挑起的字段垂直于螺旋轴的结果。
The chiral spin fluctuations and the spiral structure of the single crystal MnSi has been studied by small angle polarized neutron scattering near T-c=29 K under applied field. A weak magnetic field applied along one of the < 111 > axes produces a single domain sample with the helix wave vector along the field. The 90 degrees reorientation of the spin spiral from the [111] axis to [110] axis is observed in the field range from 130 to 180 mT in the close vicinity to T-c. Further increase of the field above 180 mT restores the original orientation of the helix and leads to the induced ferromagnetic state at 350 mT. This observation clarifies the nature of the structural spin instability found in the H-T phase diagram of MnSi by other techniques. We explain this phenomenon as a result of competition of cubic anisotropy and the spin-wave Bose condensation provoked by the field perpendicular to the helix axis.