Defect-driven extreme magnetoresistance in an I-Mn-V semiconductor

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• Technological applications require materials resistant to doping and thermal variations.
• Antiferromagnetic semiconductors present unique electronic and magnetic properties.
• Extreme magnetoresistance (MR) is a phenomenon of significant scientific and technological interest.

Purpose of the Study:

• To investigate the cause of extreme magnetoresistance in Tetragonal NaMnBi.
• To understand the role of Bi vacancies and orbital hybridization in the observed MR.
• To explore the potential of NaMnBi for microelectronic applications.

Main Methods:

• Synthesis and characterization of Tetragonal NaMnBi with varying Bi vacancy concentrations.
• Measurement of magnetoresistance under varying temperatures and magnetic fields.
• Analysis of magnetic moment re-orientation and electronic transport properties.

Main Results:

• Tetragonal NaMnBi exhibits extreme MR (>10000% at 2K, 600% at room temp/9T) when Bi vacancies are present.
• Bi vacancies introduce charge carriers, shifting electronic transport from semiconducting to metallic.
• A magnetic moment re-orientation from collinear to canted spin arrangement occurs with increasing MR.

Conclusions:

• Bi vacancies are crucial for inducing extreme MR in NaMnBi by altering electronic structure and transport.
• Hybridization between Mn and Bi orbitals appears essential for the field-induced large MR.
• NaMnBi is a unique material in its class exhibiting extreme MR, with potential for microelectronic devices.