The magnetic and structural properties of the magnetic shape memory compound Ni2Mn1.44Sn0.56
The magnetic and structural properties of the magnetic shape memory compound Ni2Mn1.44Sn0.56
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DOI：
10.1088/0953-8984/18/7/012
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发表时间：
2006-02-22
影响因子：
2.7
通讯作者：
Ziebeck, KRA
中科院分区：
文献类型：
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作者：
Brown, PJ;Gandy, AP;Ziebeck, KRA
磁性形状记忆化合物Ni_2 Mn_（1.44）Sn_（0.56）的磁化强度和高分辨中子粉末衍射测量结果证实，该化合物在319 K以下是铁磁性的，并在冷却和升温时分别在T-M = 221 K和239 K发生结构相变。高温相具有立方L2（1）结构，α = 5.973埃，过量的锰原子占据4（B）锡位。在立方相在245 K的锰的时刻在这两个网站被发现是铁磁性对齐。在4（a）位的磁矩为1.88（10）μ（B），但在4（B）位的磁矩仅为0.53（18）μ（B）/Mn。低于T-M稳定的低温相具有正交结构，空间群为Pmma，通过Bain变换a（ortho）=（a（cuB）+ B（cuB））/2; B（ortho）= c（cuB）; c（ortho）=（a（cuB）-B（cuB））与立方相相关。转变过程中晶胞体积的变化仅约为0.5%，表明尽管自发磁化强度显著下降，但原子磁矩不变。
Magnetization and high resolution neutron powder diffraction measurements on the magnetic shape memory compound Ni2Mn1.44Sn0.56 have confirmed that it is ferromagnetic below 319 K and undergoes a structural phase transition which takes place at T-M = 221 K on cooling and 239 K on warming. The high temperature phase has the cubic L2(1) structure, alpha = 5.973 angstrom, with the excess manganese atoms occupying the 4(b) tin sites. In the cubic phase at 245 K the manganese moments at both sites were found to be ferromagnetically aligned. The magnetic moment at the 4(a) sites was 1.88(10) mu(B) but it was only 0.53(18) mu(B)/Mn at the 4(b) sites. The low temperature phase stable below T-M has an orthorhombic structure with space group Pmma related to the cubic phase through a Bain transformation a(ortho) = (a(cub) + b(cub))/2; b(ortho) = c(cub); c(ortho) = (a(cub)-b(cub)). The change in cell volume in the transition is only approximate to 0.5%, suggesting that the atomic moments are unchanged although the spontaneous magnetization drops significantly.