Enhancing the Curie Temperature of Ferromagnetic Semiconductor (Ga,Mn)As to 200 K via Nanostructure Engineering

• Published in: Nano letters Vol. 11; no. 7; pp. 2584 - 2589
• Main Authors: Chen, Lin, Yang, Xiang, Yang, Fuhua, Zhao, Jianhua, Misuraca, Jennifer, Xiong, Peng, von Molnár, Stephan
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13.07.2011
• Subjects: Annealing; Arsenicals - chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Curie temperature; Exact sciences and technology; Gallium - chemistry; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Magnetic properties and materials; Magnetic properties of nanostructures; Magnetics; Manganese; Manganese - chemistry; Materials science; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Nanostructures - chemistry; Nanotechnology; Nanowires; Optimization; Physics; Quantum wires; Semiconductors; Small particles and nanoscale materials; Studies of specific magnetic materials; Surface Properties; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Temperature; Wire; molecular-beam epitaxy; magnetotransport phenomena; magnetic properties of nanostructures; Magnetic semiconductors; Curie point; Semiconductor materials; Electrical properties; Ferromagnetic materials; Annealing temperature; Manganese additions; Hall effect; Nanostructures; Gallium additions; Thin films; Nanowires; Magnetoresistance; Thermal annealing; Nanostructured materials
• DOI: 10.1021/nl201187m
• ISSN: 1530-6984; 1530-6992

We demonstrate by magneto-transport measurements that a Curie temperature as high as 200 K can be obtained in nanostructures of (Ga,Mn)As. Heavily Mn-doped (Ga,Mn)As films were patterned into nanowires and then subject to low-temperature annealing. Resistance and Hall effect measurements demonstrated a consistent increase of T C with decreasing wire width down to about 300 nm. This observation is attributed primarily to the increase of the free surface in the narrower wires, which allows the Mn interstitials to diffuse out at the sidewalls, thus enhancing the efficiency of annealing. These results may provide useful information on optimal structures for (Ga,Mn)As-based nanospintronic devices operational at relatively high temperatures.