Evidence for a coupled magnetic-crystallographic transformation in Nd5(Si0.6Ge0.4)4

作     者：C. Magen L. Morellon P. A. Algarabel M. R. Ibarra C. Ritter A. O. Pecharsky K. A. Gschneidner, Jr. V. K. Pecharsky 

作者机构：Materials and Engineering Physics Program Ames Laboratory Iowa State University Ames Iowa 50011-3020 USA and Department of Materials Science and Engineering Iowa State University Ames Iowa 50011-2300 USA 

出 版 物：《Physical Review B》 (Phys. Rev. B Condens. Matter Mater. Phys.)

年 卷 期：2004年第70卷第22期

页      面：224429-224429页

核心收录：

学科分类：0808[工学-电气工程] 0809[工学-电子科学与技术（可授工学、理学学位）] 07[理学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0702[理学-物理学] 

基　　金：U.S. Department of Energy, USDOE, (W-7405-ENG-82) U.S. Department of Energy, USDOE Basic Energy Sciences, BES 

摘      要：We have performed a detailed study of the magnetic and structural properties of the compound Nd5(Si0.6Ge0.4)4 by means of neutron powder diffraction, magnetization, linear thermal expansion, and magnetostriction experiments. A coupled magnetic and crystallographic first-order transformation from a room-temperature monoclinic Gd5Si2Ge2-type paramagnetic state to a low-temperature orthorhombic Gd5Si4-type ferromagnetic structure takes place on cooling at ∼68K. This magnetostructural transition shifts towards higher temperatures by the application of an external magnetic field at a rate of 0.11(1)K∕kOe, which is lower than the ∼0.6to∼0.3K∕kOe observed in the Gd5(SixGe1−x)4 and Tb5(SixGe1−x)4 compounds. The magnetostructural transformation cannot be completed in the isothermal regime by a 120kOe magnetic field. It is suggested that the single-ion anisotropy of the Nd ions hinders the completion of the field-induced transformation. The existence of a simultaneous magnetic and crystallographic transformation in this alloy, which is in sharp contrast with other previously studied Nd5(SixGe1−x)4 alloys, is discussed in terms of the role of interstitial impurities in triggering and coupling/decoupling the crystallographic transition.