Evolution of two-step magnetic transition on nanogranular Gd5Si1.3Ge2.7 thin film

Thumbnail Image
Date
2020-02-25
Authors
Belo, J. H.
Pires, A. L.
Gomes, I. T.
Sousa, J. B.
Hadimani, R. L.
Jiles, David
Pereira, A. M.
Araújo, J. P.
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Person
Jiles, David
Distinguished Professor Emeritus
Research Projects
Organizational Units
Organizational Unit
Organizational Unit
Organizational Unit
Materials Science and Engineering
Materials engineers create new materials and improve existing materials. Everything is limited by the materials that are used to produce it. Materials engineers understand the relationship between the properties of a material and its internal structure — from the macro level down to the atomic level. The better the materials, the better the end result — it’s as simple as that.
Journal Issue
Is Version Of
Versions
Series
Department
Ames National LaboratoryElectrical and Computer EngineeringMaterials Science and Engineering
Abstract

A multi-functional Gd5Si1.3Ge2.7 thin film deposited by pulsed laser ablation in the form of an ensemble of nanoparticles was studied for 18 thermal cycles via electron transport measurements together with structural and magnetic characterization. A general negative thermal dependency of the resistivity (ρ) is observed, which contrasts with the metallic-like behavior observed in bulk Gd5SixGe4-x compounds. This general trend is interrupted by a two-step, positive-slope transition in ρ(T) throughout the [150,250]K interval, corresponding to two consecutive magnetic transitions: a fully coupled magnetostructural followed by a purely magnetic order on heating. An avalanche-like behavior is unveiled by the ∂ρ/∂T(T) curves and is explained based on the severe strains induced cyclically by the magnetostructural transition, leading to a cycling evolution of the transition onset temperature (∂T''h/∂n ~ 1.6 K/cycle , n being the number of cycles). Such behavior is equivalent to the action of a pressure of 0.56 kBar being formed and building up at every thermal cycle due to the large volume induced change across the magnetostructural transition. Moreover the thermal hysteresis, detected in both ρ and magnetization versus temperature curves, evolves significantly along the cycles, decreasing as n increases. This picture corroborates the thermal activation energy enhancement - estimated via an exponential fitting of the ∂ρ/∂T(T) in the avalanche regime. This work demonstrates the importance of using a short-range order technique, to probe both pure magnetic and magnetostructural transitions and their evolution with thermal cycles.

Comments

This is a peer-reviewed, un-copyedited version of an article accepted for publication/published in Journal of Physics: Condensed Matter. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at DOI: 10.1088/1361-648X/ab79f9. Posted with permission.

Description
Keywords
Citation
DOI
Copyright
Wed Jan 01 00:00:00 UTC 2020
Collections