Magnetic Polarons and Large Negative Magnetoresistance in GaAs Nanowires Implanted with Mn Ions

• Published in: Nano letters Vol. 13; no. 11; pp. 5079 - 5084
• Main Authors: Kumar, Sandeep, Paschoal, Waldomiro, Johannes, Andreas, Jacobsson, Daniel, Borschel, Christian, Pertsova, Anna, Wang, Chih-Han, Wu, Maw-Kuen, Canali, Carlo M, Ronning, Carsten, Samuelson, Lars, Pettersson, Håkan
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13.11.2013
• Subjects: Applied sciences; Condensed Matter Physics; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electronics; Engineering and Technology; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Gallium arsenide; Gallium arsenides; GaMnAs; hopping transport; Ion-implantation; Kondenserade materians fysik; magnetic polarons; Magnetoresistance; Magnetoresistivity; Manganese; Materials science; Molecular electronics, nanoelectronics; Nano Technology; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanospintronics; Nanoteknik; Nanowires; Negative magnetoresistance; Physics; Polarons; Quantum wires; self-assembly; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Specific phase transitions; spin-glass; spintronics; Structural transitions in nanoscale materials; Superconducting quantum interference devices; Teknik; spintronics; ion-implantation; (Ga,Mn)As; Nanowires; hopping transport; magnetic polarons; spin-glass; negative magnetoresistance; Magnetic polarons; Temperature dependence; Negative magnetoresistance; Spin glasses; Gallium arsenides; Transition temperature; Manganese additions; Low field; Phase transitions; III-V compound; SQUID devices; Nanostructured materials; III-V semiconductors
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/nl402229r

We report on low-temperature magnetotransport and SQUID measurements on heavily doped Mn-implanted GaAs nanowires. SQUID data recorded at low magnetic fields exhibit clear signs of the onset of a spin-glass phase with a transition temperature of about 16 K. Magnetotransport experiments reveal a corresponding peak in resistance at 16 K and a large negative magnetoresistance, reaching 40% at 1.6 K and 8 T. The negative magnetoresistance decreases at elevated temperatures and vanishes at about 100 K. We interpret our transport data in terms of spin-dependent hopping in a complex magnetic nanowire landscape of magnetic polarons, separated by intermediate regions of Mn impurity spins, forming a paramagnetic/spin-glass phase.