Correlation between magnetostriction and magnetic structure in pseudobinary compounds Tb(Co1-xFex)2

Yue Wang,Tieyan Chang,Sen Yang,Chen Wu,Tianyu Ma,Changsheng Zhang,Xinqi Zheng,Xiaoqi Liao,Yu Wang,Guangai Sun,Mi Yan,Xiping Chen,Chao Zhou

doi:10.1063/1.4991734

Abstract

Giant low-field magnetostriction has been achieved in pseudobinary Laves phase compounds RR’T2 (R and R’: rare earth elements; T: transition metal elements) around the ferromagnetic - ferromagnetic (ferro.-ferro.) transition temperature. Evolution of the magnetic structure across such transition requires comprehensive investigation. In this work, pseudobinary system Tb(Co1-xFex)2 is selected to investigate the evolution of local magnetic moment, for which two end terminals TbCo2 and TbFe2 possess the rhombohedral (R) structure at the ferromagnetic state but with different magnetic ordering temperatures (TC). Magnetometry measurements reveal that a composition independent ferromagnetic - ferromagnetic transition occurs at ∼100 K despite the increased Curie temperature TC with raised Fe concentration in the Tb(Co1-xFex)2. Synchrotron XRD data reveal that both the lattice parameter and the lattice strain along the &lt;111&gt; direction are abnormally temperature dependent, accompanied with experimentally observed magnetostriction abnormality at 100 K. In-situ neutron powder diffraction (NPD) results show that the local magnetic moments of T2 (9e site) atoms are also abnormally temperature dependent, which is larger at 100 K than that at a lower temperature 50 K. Such findings indicate close correlations between the magnetic structure and the magnetostrictive effect in the pseudobinary RT2 compounds.

Highlights

Cubic Laves phase compounds RT 2 have attracted intensive interest due to their strong magnetoelastic effect, which origins from the coexistence and strong interaction of magnetic moments of highly localized 4f electrons and itinerant 3d electrons.[1,2,3,4,5,6,7,8,9] They have been widely regarded as the most important class of magnetostrictive materials and are appealing for applications in magnetomechanical transducers, actuators, and energy harvesting systems
075311-2 Wang et al AIP Advances 7, 075311 (2017). Anisotropy compensation for these systems has usually been achieved at the ferro.-ferro. transition, which has previously been known as the spin reorientation transition (SRT )
Despite that the ferromagnetic morphotropic phase boundary (MPB) stimulates the design of materials with giant low-field magnetostriction,[18,19,20] insights on the magnetic structure change across the ferro. - ferro. transition in the pseudobinary RT 2 systems is lacking

Summary

Introduction

Cubic Laves phase compounds RT 2 have attracted intensive interest due to their strong magnetoelastic effect, which origins from the coexistence and strong interaction of magnetic moments of highly localized 4f electrons and itinerant 3d electrons.[1,2,3,4,5,6,7,8,9] They have been widely regarded as the most important class of magnetostrictive materials and are appealing for applications in magnetomechanical transducers, actuators, and energy harvesting systems. Recent high resolution synchrotron XRD data have revealed that SRT as in the TbxDy1-xCo2 and TbxDy1-xFe2 systems,[14,15] involves crystal structural change from a rhombohedral (R 3 ̄ m) symmetry with the spontaneous magnetization MS // [111] into the tetragonal symmetry (I41/amd) with MS// [001].

Results

Conclusion