Phase relationships and structural, magnetic, and thermodynamic properties of alloys in the pseudobinary Er5Si4-Er5Ge4 system

Date
2004-10-29
Authors
Lograsso, Thomas
Pecharsky, A.
Gschneidner, Karl
Schlagel, Deborah
Pecharsky, Vitalij
Schlagel, Deborah
Lograsso, Thomas
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Research Projects
Organizational Units
Ames Laboratory
Organizational Unit
Journal Issue
Series
Department
Ames Laboratory
Abstract

The room temperature crystal structures of Er5SixGe4−x alloys change systematically with the concentration of Ge from the orthorhombic Gd5Si4-type when x=4, to the monoclinic Gd5Si2Ge2 type when 3.5⩽x⩽3.9 and to the orthorhombic Sm5Ge4 type forx⩽3. The Curie-Weiss behavior of Er5SixGe4−x materials is consistent with the Er3+ state. The compounds order magnetically below 30 K, apparently adopting complex noncollinear magnetic structures with magnetization not reaching saturation in 50 kOe magnetic fields. In Er5Si4, the structural-only transformation from the monoclinic Gd5Si2Ge2-type to the orthorhombic Gd5Si4-type phase occurs around 218 K on heating. Intriguingly, the temperature of this polymorphic transformation is weakly dependent on magnetic fields as low as 40 kOe (dT∕dH=−0.058 K∕kOe) when the material is in the paramagnetic state nearly 200 K above its spontaneous magnetic ordering temperature. It appears that a magnetostructural transition may be induced in the 5:4 erbium silicide at ∼18 K and above by 75 kOe and higher magnetic fields. Only Er5Si4 but none of the other studied Er5SixGe4−x alloys exhibit magnetic field induced transformations, which are quite common in the closely related Gd5SixGe4−x system. The magnetocaloric effects of the Er5SixGe4−x alloys are moderate.

Comments

This article is from Physical Review B 70 (2004): 144419, doi:10.1103/PhysRevB.70.144419.

Description
Keywords
Citation
DOI
Collections