Magnetic and transport characteristics in Gd 0.925 La 0.075 Mn 2 Ge 2 with two-dimensional alignment of Mn atoms
Magnetic and transport characteristics in Gd 0.925 La 0.075 Mn 2 Ge 2 with two-dimensional alignment of Mn atoms
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DOI：
10.1103/physrevb.63.174440
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发表时间：
2001-04
影响因子：
3.7
通讯作者：
T. Fujiwara;H. Fujii;T. Shigeoka
中科院分区：
文献类型：
--
作者：
T. Fujiwara;H. Fujii;T. Shigeoka
本文介绍了我们最近对具有${\mathm{thcr}}{2}{\mathm{Si}}{2}$型层状结构的金属间化合物${\mathrm{Gd}}_{0.925}{\mathrm{La}}_{0.075}{\mathrm{Mn}}_{2}{\mathrm{Ge}}_{2}$的磁性和输运性质的实验结果。结果表明，随着温度的降低，${\mathrm{Gd}}_{0.925}{\mathrm{La}}_{0.075}{\mathrm{Mn}}_{2}{\mathrm{Ge}}_{2}$在居里温度{T}{T1}以下有两种一级转变：从斜面亚铁磁态到非共线反铁磁态，从非共线反铁磁态到重入斜面亚铁磁态。在${T}_{T2}和${T}_{T3}之间，在相对较低的磁场中出现了由非共线反铁磁性到倾斜亚铁磁性的超磁感应，并伴随着分形状的多步转变，即所谓的‘魔鬼阶梯情况’。此外，在场致变磁转变过程中还观察到了负的巨磁电阻效应$(\ensuremath{\Delta}\ensuremath{\rho}/\ensuremath{\rho}\ensuremath{\sim}15%)$。根据用单晶${\mathrm{Gd}}_{0.925}{\mathrm{La}}_{0.075}{\mathrm{Mn}}_{2}{\mathrm{Ge}}_{2}$和{{TbMn}}{2}{\mathm{Ge}}{2}综合测量电阻率的结果，讨论了这种负巨磁电阻效应的机制.这些反常特征可能是Mn原子的层状结构和二维排列的特征.
We present our recent experimental results on magnetic and transport properties in intermetallic compound ${\mathrm{Gd}}_{0.925}{\mathrm{La}}_{0.075}{\mathrm{Mn}}_{2}{\mathrm{Ge}}_{2}$ with the ${\mathrm{ThCr}}_{2}{\mathrm{Si}}_{2}$-type layered structure. The results obtained indicate that ${\mathrm{Gd}}_{0.925}{\mathrm{La}}_{0.075}{\mathrm{Mn}}_{2}{\mathrm{Ge}}_{2}$ reveals two kinds of first order transitions below the ferrimagnetic Curie temperature ${T}_{t1},$ from canted ferrimagnetic to noncollinear antiferromagnetic states and from noncollinear antiferromagnetic to reentrant canted ferrimagnetic states at ${T}_{t2}$ and ${T}_{t3}$ with decreasing temperature. Between ${T}_{t2}$ and ${T}_{t3},$ a field induced metamagnetism from noncollinear antiferromagnetism to canted ferrimagnetism appears at relatively lower fields, accompanied with fractal-like multistep transitions, the so called ``devil's stair case.'' Furthermore, a negative giant magnetoresistance effect $(\ensuremath{\Delta}\ensuremath{\rho}/\ensuremath{\rho}\ensuremath{\sim}15%)$ is also observed at the field induced metamagnetic transition. The mechanism of this negative GMR is discussed on the basis of the results of comprehensive measurements of the resistivities using single-crystalline ${\mathrm{Gd}}_{0.925}{\mathrm{La}}_{0.075}{\mathrm{Mn}}_{2}{\mathrm{Ge}}_{2}$ and ${\mathrm{TbMn}}_{2}{\mathrm{Ge}}_{2}.$ These unusual features might be characteristic of layered structure, two-dimensional alignment of Mn atoms.