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Meeting 2016 TMS Annual Meeting & Exhibition
Symposium Advanced Magnetic Materials: An FMD Symposium in Honor of Michael E. McHenry
Presentation Title Observation of ‘Re-entrant Inverse-magnetocaloric Phenomenon’ and Asymmetric Magnetoresistance Behavior in RFe5Al7 (R= Gd and Dy)
Author(s) Venkatesh Chandragiri, Kartik Iyer K Iyer, E.V. Sampathkumaran
On-Site Speaker (Planned) E.V. Sampathkumaran
Abstract Scope The magnetocaloric effect (MCE) of a few rare-earth based ferrimagnets containing two magnetic sublattices, attracted some attention a few decades ago, as there is a sign cross-over at the magnetic compensation point. We consider it important to further expand our knowledge on MCE phenomenon in this respect by focusing on other multi-sublattice magnetic systems. We have noted that the rare-earth intermetallics of the type, RFe5Al7, crystallizing in ThMn12-type tetragonal (I4/mmm) structure, provide an ideal opportunity for the same. After initial investigations in 1982, the interest in this family got revived only very recently. With the primary motivation of understanding of MCE behavior of such a complex ferrimagnet, we have undertaken a magnetic study of two members, namely R= Gd and Dy, of this family. These two members order ferrimagnetically at 250 and 223 K respectively. Primary conclusions are: (i) There are multiple sign-crossovers in the temperature (T) dependence of isothermal entropy change (ΔS) in the case of Dy compound; in addition to nil ΔS at the magnetic compensation point known for two-magnetic-sublattice systems, there is an additional sign-crossover at low temperatures, as though there is a ‘re-entrant inverse magnetocaloric’ phenomenon. Corresponding sign reversals could also be observed in the magnetoresistance data. (ii) The plots of magnetoresistance versus magnetic field are found to be unusually asymmetric with the reversal of the direction of magnetic-field (H) well below TN for both compounds. We attribute these to subtle changes in spin orientations of R and Fe moments induced by T and H.
Proceedings Inclusion? Planned: None Selected

OTHER PAPERS PLANNED FOR THIS SYMPOSIUM

A Solid-State Approach to Alnico-based Permanent Magnets
A Study of Magnetocaloric Effect and Increased Working Temperature Range in a Heusler Mn50Ni37In10Co3 Unidirectional Crystal
Advanced Magnetic Materials for High Power Density, High Efficiency Electrical Systems
Advanced Soft Magnetic Material Enabled Devices and Components for Emerging Energy Applications
Application of Soft Magnetic Nanocomposites in Power Electronics
Artificial Magnetic Lattices and Their Applications
Caloric Effects in Ni-Mn-Sn Ribbons
Cation Disorder in Nanoparticle and Thin Film Ferrite Systems
CC-1: Direct Measurements of Magnetoelastic Coupling in Shape Memory Alloy
CC-2: FeCo Alloys to Cobalt Ferrite: Synthesis Considerations, Structural Characterization and Magnetic Properties
CC-3: Effect of Processing Route and Alloying Substitutions on the Microstructure and Magnetic Properties of Ferrite Magnets
CC-4: Structural, Microstructure and Magnetic Properties of Superparamagnetic MnxMg1-xFe2O4 Powders Prepared through Co-precipitation Method
CC-5: Tailoring of Magnetic Softness of Fe-Ni Based Magnetic Microwires
CC-6: Synthesis and Characterization of CFO/BCZT Core-shell Structure for Magnetoelectric Application
CC-7: Infiltration Process in Permanent Magnets for Coercivity Enhancement
Co-based Rare Earth Free Permanent Magnet Materials
Comparison of Grain Boundary Diffusion Processes (GBDP) in Nd-Fe-B Permanent Magnets
Current Trends in Giant Magnetoimpedance Materials Research
Design of Nano-crystalline Soft Magnetic Alloys: Electronic Structure
Developing Permanent Magnet Alloys via Rapid Assessment Methodologies
Dy-free High Coercivity Nd-Fe-B Permanent Magnets
Enhanced Powder-processed Alnico Magnets by Thermal Gradient Control
FeCo Alloy Mesochains by Co-precipitation
First Order Reversal Curve (FORC) Analysis of Iron-Nickel Zinc Ferrite Nanocomposites
Heavy Rare Earths at Grain Boundaries to Achieve Maximum Coercivity in Industrial Magnetic Materials
High Silicon Iron Alloy Strips by Single-step Shear Deformation
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Magnetic and Structural Correlation of Ferrite-coated Ferrous Powder Soft Magnetic Composites
Magnetic Anisotropy in Nanocomposites – What More Do We Know, What Questions Remain?
Magnetic Field Induced Large Strain by Reversible Phase Transformation on Metamagnetic Shape Alloys
Magnetic Field Mapping at the Nanoscale in the Transmission Electron Microscope
Magnetic Materials and Minerals in Planetary Exploration
Magnetic Nanoparticle-based Solder Composites for Electronic Packaging Applications
Magnetic Phases in the Systems Mn-Bi, Mn-Sb, and Mn-Bi-Sb
Magnetic Properties of Size-controlled Ni Nanoparticles Modified with Tri-n-octylphosphine
Magnetocaloric Effects in Ni-Mn-Al Type Alloys
Magnetocaloric Materials: From Advanced Characterization to Industrial Application
Microstructural Effects of Thermomagnetic Treatments in Sintered Nd-Fe-B Magnets
Nanocomposite Soft Magnetic Alloys: Two Decades of Progress
Novel Applications of Magnetic Nano-composites in Semiconductor Packaging
Nucleation Mediated Nanostructures in Soft Magnetic Fe-Si-B Based Alloys (Invited)
Observation of ‘Re-entrant Inverse-magnetocaloric Phenomenon’ and Asymmetric Magnetoresistance Behavior in RFe5Al7 (R= Gd and Dy)
Often Overlooked Aspects of the Symmetry of Magnetic Materials
Optimizing Process Parameters for Additive Manufacturing of Bonded Permanent Magnets
Preparation and Characterization Fe-Pt and Fe-Pt-M (M=B, SI) Microwires
Processes for the Recycling of Rare Earth Permanent Magnets
Processing and Characterization of Magnetic Materials for Magnetic Refrigeration, High Frequency Power Conversion, and High Temperature Electrical Machine Applications
Rapid Crystallization of Non-equilibrium Rare-earth and Non-rare-earth Permanent Magnet Materials
Rare Earth Lean Nanocrystalline Permanent Magnets
Recent Studies on Half Metallic Ferromagnets Belonging to the Heusler Family
Soft-Phase Engineering and Hard-Phase Engineering in Exchange-Coupled Nanocomposite Magnets
Synthesis of Fe3O4 Nanostructures and Their Potential Applications
Synthesis of Submicron R-Co and R-Fe-B Particles by the Mechanochemical Process
Textures of Non-oriented Electrical Steels Processed by Skew Rolling
The Role of Alloying Elements on the Magnetostriction of Fe
Transition Metal Based Magnetocaloric Materials
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Unusual Magneto-Elasticity of Fe-(Co), Ga, (Al, Ge, Si) Alloys

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