INVESTIGATIONS OF MAGNETIC-ANISOTROPY IN THE COMPLEX LOW-TEMPERATURE PHASE IN FE2MNSI

Low-field (100 Oe) DC susceptibility zero-held-cooled (ZFC) and field- cooled (FC) measurements (using a SQUID magnetometer) have been made o n a Fe2MnSi single crystal. This compound exhibits a complex magnetic behaviour involving a transition from a paramagnetic state to a ferrom agnetically ordered state at T-c similar to 220 K, followed by a trans ition to a low-temperature reordering phase at T-R similar to 60 K. Re sults confirm previously observed demagnetising effects from polycryst alline samples with similar compositions. Also, the ZFC measurements a long separate crystallographic directions show that the magnetization increases most readily in the [1 0 0] direction compared with that of [1 1 0], indicating a form of anisotropy in the complex low-temperatur e phase in Fe3-xMnxSi alloys. The FC measurements at this held are dem agnetisation limited even in the re-ordered phase. (C) 1998 Elsevier S cience B.V. All rights reserved.