Room-Temperature Ferromagnetism in Cu Doped GaN Nanowires

Abstract

We report magnetism in Cu doped single-crystalline GaN nanowires. The typical diameter and the length of the Ga1-xCuxN nanowires (x = 0.01, 0.024) are 10-100 nm and tens of micrometers, respectively. The saturation magnetic moments are measured to be higher than 0.86 microB/Cu at 300 K, and the Curie temperatures are far above room temperature. Anomalous X-ray scattering and X-ray diffraction measurement make it clear that Cu atoms substitute the Ga sites, and they largely take part in the wurtzite network of host GaN. X-ray absorption and X-ray magnetic circular dichroism spectra at Cu L(2,3) edges show that doped Cu has local magnetic moment and the electronic configuration of it is mainly 3d9 but mixed with a small portion of trivalent component. It seems that the ionocovalent bonding nature of Cu 3d orbital with surrounding semiconductor medium makes Cu atom a mixed electron configuration and local magnetic moments. These outcomes suggest that the Ga1-xCuxN system is a room-temperature ferromagnetic semiconductor.

Cu-doped nitrides: Promising candidates for a nitride based spin-aligner

“…In contrast, DFT calculations by Rosa and Ahuja [10] showed only weak ferromagnetism, making the material unsuitable for spintronic applications. Experimental results were reported for Cu-doped nitride nanowires [11][12][13], Cu-implanted GaN [14,15] and CVD grown Cu-doped GaN [16]. Initial results for Cu-doped GaN grown by molecular beam epitaxy were reported by our group [17].…”

Ferromagnetism in undoped One-dimensional GaN Nanowires

“…Since then, there have been continuous reports on RTFM of semiconductors 3 including wurtzite Gallium Nitride (GaN) doped with transition metal ions 4,5 and other non-magnetic impurities. 6 However, the origin of ferromagnetism remains controversial and there are issues such as clustering, segregation, precipitation and formation of secondary phase of the dopants which remain unaddressed. 7,8 On the other hand, recent intriguing observation of ferromagnetism in undoped wide band gap oxide semiconductors has led to the idea of creating magnetism by the influence of defects such as surface impurities, vacancies, interstitials, grain boundaries and lattice distortions at the nanoscale.…”

Understanding the Room Temperature Ferromagnetism in GaN Nanowires with Pd Doping

“…This approach is pivotal in the formulation of spin-based electronics, or spintronics, which has emerged as a potential alternative to conventional charge-based electronics [6]. Diluted magnetic semiconductor nanowires (DMS-NWs) [2,7,8] have, therefore, attracted significant interest in recent years due to the possibility of expanding devices functionality using electronic spin as an additional degree of freedom. Moreover, shape anisotropy of DMS-NWs may potentially allow for a reduced magnetostatic energy and, therefore, easier magnetization of the NWs along the growth direction.…”