Activation and Enhancement of Room-Temperature Ferromagnetic Exchange in (Cu,N)-codoped In₂O₃ Dilute Magnetic Nanowires

Abstract

Spin manipulation in dilute magnetic oxide nanowires is an important topic for achieving nanometer-sized spin-based magnetic devices. In this study, single-crystalline Cu-doped and (Cu,N)-codoped In 2 O 3 nanowires were grown through a chemical vapor deposition method using In 2 O 3 and CuO powders as precursor materials. The detailed structural analyses indicate that the Cu-doped and (Cu,N)-codoped In 2 O 3 nanowires are of pure cubic bixbyite phase of In 2 O 3 . X-ray photoelectron spectroscopy provides obvious evidence that the Cu and N dopants are in the +1 and −3 valence states, respectively, and some oxygen vacancy defects are introduced into the doped In 2 O 3 nanowires. The Cu K-edge X-ray absorption fine structure spectroscopy further reveals that the doped Cu atoms are incorporated substitutionally into the In 2 O 3 host lattice at In sites without the formation of Cu metal clusters and Cu oxides secondary phases. The Cu dopants induce a large σ Cu−O 2 , which is due to the enhancement of lattice shrinkage and the relaxation of the oxygen environment of Cu atoms upon substitution. The magnetic measurements indicate that both the doped nanowires exhibit intrinsic room-temperature ferromagnetic ordering and the saturation magnetization remarkably increases in the (Cu,N)-codoped In 2 O 3 nanowires. The N codoping induces obvious spin splitting by a crystal field and strong p−d hybridization between the Cu 3d and N 2p states, which causes ferromagnetic coupling between two Cu atoms and is proved by first-principles calculations. These results demonstrate that the bound magnetic polaron mechanism plays a critical role in the observed intrinsic ferromagnetism for the (Cu,N)-codoped In 2 O 3 nanowires.

First-Principles Study of the Effect of Native Defects on Spin Polarization and Exchange Coupling Interaction in Semimetal V3O4

“…Owing to the lowest defect formation energies, the highest magnetic moments and spin polarization degrees of neutral V vacancy defects at A and B sites in contrast to other defects, we mainly study the role of the neutral V vacancy defect at different sites in influencing the magnetic coupling exchange of the V 3 O 4 material. Curie temperature is determined by exchange coupling strength, which further depends on the difference in the total energies (Δ E ) between the AFM and FM states. − As illustrated in Figure , the FM state is obtained from the collinear spin-polarized optimization of identical spin directions of the V atoms, and the AFM state is just reversing the inter-plane V spin directions in the lattice. The calculated positive and negative Δ E values correspond to FM and AFM ground states, separately.…”

Magnetic properties of Mn-doped InSb nanowires from first principles

“…Since an experimental reports of T C reaching 200K in (Ga,Mn)As by patterning a heavily Mn-doped (Ga,Mn)As films into NWs [23], this success has inspired researchers to be interested in DMS NWs that takes advantage of the quantum size effect and surface effect of the NW. At the experimental level, the room temperature DMS NWs were developed using Mn-doped GaN NWs [24], Co-doped GaN NWs [25,26], Co-doped ZnO NWs [27], and (Cu,N)-codoped In 2 O 3 NWs [28]. Theoretically, Zhang et al suggested that the magnetic moment and the ferromagnetic states in (Ga,Mn)As NWs can be effectively regulated by the surface dangling bonds [29].…”