Phase relations, single crystal growth, and characterization of metallic antiferromagnets

Gebre, Mebatsion Sileshi

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https://hdl.handle.net/2142/120429 Copy

Description

Title

Phase relations, single crystal growth, and characterization of metallic antiferromagnets

Author(s)

Gebre, Mebatsion Sileshi

Issue Date

2023-04-27

Director of Research (if dissertation) or Advisor (if thesis)

Shoemaker, Daniel P

Doctoral Committee Chair(s)

Shoemaker, Daniel P

Committee Member(s)

• Hoffmann, Axel
• Schleife, Andre
• Mahmood, Fahad

Department of Study

Materials Science & Engineerng

Discipline

Materials Science & Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Metallic antiferromagnets
• crystal growth
• magnetocrystalline anisotropy

Abstract

Metallic antiferromagnets (AFM) are actively researched in materials science and physics as spintronic material candidates and for emerging physical phenomena. Understanding the phase relations in relevant chemical systems to grow and characterize high quality AFM single crystals is integral to learning their fundamental physical and magnetic properties. Magnetic ordering can be studied in materials containing transition 3d metals or in lanthanide-containing compounds. In this work, two families of materials that host metallic or topological insulator AFM of interest in the Eu-Sn-In-P and Mn-Au-Bi systems are studied. Special focus is afforded to exploring the phase stability, property-targeted chemical modifications, single crystal growth, and anisotropic characterization of magnetic properties. The high temperature metallic antiferromagnet Mn2Au, has been proposed as a suitable candidate for spintronics applications via several prior thin-film and polycrystal studies, as well as first principles calculations. In this work, a single crystal growth method was developed and optimized using bismuth flux to obtain the first mm-scaled bulk single crystals of the material. The phase purity, nuclear and magnetic structures, crystal orientations, magnetic anisotropy and electric transport properties of the single crystals are discussed in comparison to existing literature. Chemical substitution targeting materials discovery and band structure engineering in the magnetic topological insulator candidate, EuSn2P2, is explored using experimental substitutions on the Eu and Sn sites, informed by a review of the literature and density functional theory calculations (DFT). Partial alloying in the Eu(Sn/In)2P2 system is confirmed and proposed as an alternative route towards chemically tuning the band structure of EuSn2P2.The structure of a new quaternary phase, orthorhombic Eu2InSnP3, is solved as an addition to this phase space. The intrinsic material properties of these materials are probed on single crystals using a variety of transport, magnetic properties, and spectroscopy techniques.

Graduation Semester

2023-05

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/120429

Copyright and License Information

Copyright 2023 Mebatsion Gebre

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