凝聚态物理
铁磁性
格子(音乐)
正交晶系
相变
各向异性
六边形晶格
不稳定性
顺磁性
散射
材料科学
晶体结构
物理
反铁磁性
化学
量子力学
结晶学
声学
作者
Valeri Petkov,A. Zafar,T. Durga Rao,Milinda Abeykoon
标识
DOI:10.1088/1361-648x/acd042
摘要
Using variable temperature x-ray total scattering in magnetic field, we study the interaction between lattice and magnetic degrees of freedom in MnAs, which loses its ferromagnetic order and hexagonal ('H') lattice symmetry at 318 K to recover the latter and become a true paramagnet when the temperature is increased to 400 K. Our results show that the 318 K transition is accompanied by highly anisotropic displacements of Mn atoms that appear as a lattice degree of freedom bridging the 'H' and orthorhombic phases of MnAs. This is a rare example of a lowering of an average crystal symmetry due to an increased displacive disorder emerging on heating. Our results also show that magnetic and lattice degrees of freedom appear coupled but not necessarily equivalent control variables for triggering phase transitions in strongly correlated systems in general and in particular in MnAs.
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