中文摘要：

我们用光学浮区法生长了稀土正铁氧体Dy0．9Sm0．1FeO3（DSFO）单晶，并通过劳厄衍射法确定了单晶样品的方向．对DSFO单晶的磁性研究表明：在DyFe03中掺杂10％的Sm后，体系的自旋重取向转变温度从51K（DyFeO3）降低到9K，而且相变过程变成了由Г4到Г42再到Г1．在12—300K区间DSFO处于Г4组态，沿c方向Fe离子磁晶格有一个净的磁矩和一个由它诱导的稀土离子的净磁矩．稀土磁矩和Fe磁矩之间本征地反平行耦合，但一个较小的磁场可以改变反平行耦合到平行耦合．在场冷降温模式下的磁化-温度曲线测试中，我们发现在不同的磁场下磁化曲线会在不同的位置发生跳变；这一现象由稀土磁矩和Fe磁矩之间的平行反平行转变导致，有望作为特定条件下的自旋开关而应用于自旋电子学器件中．

英文摘要：

We report the spin configuration and magnetization reversal in a Dy0. 9 Sm0.1FeO3 （DSFO） orthoferrite single crystal which is grown by the Optical-Floating-Zone method. The Laue camera is conducted to orient the single crystal. We employe a Superconduct Quantum Interfere Device （SQUID） to perform the magnetic characterization and find that： 1） the apparance of Sm would decrease the interaction between Dy-Fe, which thus decreases the spin reorientation temperature from 51 K （for DyFeO3 ） to about 9 K （for DSFO）; 2） the spin reorientation type is verified to be Г4 Г42 to Г1, exhibiting another effect of Sm doping; 3 ） the canted antiferromagnetic Fe sublattice contributes to a weak ferromagnetic component FFe, which could also induce a rare- earth-ions weak ferromagnetic component FR below about 200 K. FFe and FR desire to be antiparallel to each other,but possess a quite small energy difference from parallel coupling state. Thus, the small applied field would keep the weak ferromagnetic components parallel, as a metastable state, in the cooling process, until a certain point where a jumping occurs and FR flips to the opposite direction. The study would lead to a better understanding of spin reorientations in rare-earth orthoferrites, as well as precisely predict the jumping in field cooling magnetization curves, which will lead to the exploring in spin switching area.