Magnetic-field-enhanced forbidden modes in Co-doped ZnO thin films revealed by Raman scattering

Ji, J. T.; Zhang, A. M.; Xia, Tian‐Long; Cao, Qiang; Liu, G. L.; Hou, Dong; Zhang, Q. M.

doi:10.1103/physrevb.82.014408

Cited by 9 publications

(5 citation statements)

References 26 publications

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“…With increasing of concentration of V + O centers, greater the volume occupied by bound magnetic polarons and larger the probability of Mn ions overlapping leads to a long-range ferromagnetic ordering. When neighboring polarons overlap, the spins of the two-polarons tend to align in the direction of external magnetic field [ 49 ]. These effects can be responsible for long-range order ferromagnetism in our Mn doped ZnO nanorods at room temperature.…”

Section: Resultsmentioning

confidence: 99%

Raman Submicron Spatial Mapping of Individual Mn-doped ZnO Nanorods

et al. 2017

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ZnO nanorods (NRs) arrays doped with a large concentration of Mn synthesized by aqueous chemical growth and were characterized by SEM, photoluminescence, Raman scattering, magnetic force microscopy (MFM). By comparison of spectra taken on pure and Mn-doped ZnO NRs, a few new Raman impurity-related phonon modes, resulting from the presence of Mn in the investigated samples. We also present a vibrational and magnetic characterization of individual lying nanorods using Raman and MFM imaging. Confocal scanning micro-Raman mapping of the spatial distribution of intensity and frequency of phonon modes in single Mn-doped ZnO NRs nanorods is presented and analyzed for the first time. Mn-related local vibrational modes are also registered in Raman spectra of the single nanorod, confirming the incorporation of Mn into the ZnO host matrix. At higher Mn concentration the structural transformation toward the spinel phase ZnMn2O4 and Mn3O4 is observed mainly in 2D bottom layers. MFM images of Mn-doped ZnO NR arrays and single nanorod were studied in nanoscale at room temperature and demonstrate magnetic behavior. The circular domain magnetic pattern on top of single nanorod originated to superposition of some separate domains inside rod. This demonstrates that long-range ferromagnetic order is present at room temperature. Aligned Mn-doped ZnO NRs demonstrates that long-range ferromagnetic order and may be applied to future spintronic applications.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-017-2127-4) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Raman Submicron Spatial Mapping of Individual Mn-doped ZnO Nanorods

et al. 2017

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“…Moreover, even nonmagnetic materials such as CaB 6 [12][13][14] and the semiconducting oxide TiO 2 [15] may exhibit room-temperature ferromagnetism, an intriguing phenomenon possibly driven by the presence of magnetic and/or nonmagnetic impurities. This kind of phenomena has attracted a great deal of attention in recent years and has emerged as one important branch in condensed matter physics and materials science [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Far-from-equilibrium growth of magnetic thin films with Blume-Capel impurities

2015

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We investigate the irreversible growth of (2+1)-dimensional magnetic thin films. The spin variable can adopt three states (s(I)=±1,0), and the system is in contact with a thermal bath of temperature T. The deposition process depends on the change of the configuration energy, which, by analogy to the Blume-Capel Hamiltonian in equilibrium systems, depends on Ising-like couplings between neighboring spins (J) and has a crystal field (D) term that controls the density of nonmagnetic impurities (s(I)=0). Once deposited, particles are not allowed to flip, diffuse, or detach. By means of extensive Monte Carlo simulations, we obtain the phase diagram in the crystal field vs temperature parameter space. We show clear evidence of the existence of a tricritical point located at D(t)/J=1.145(10) and k(B)T(t)/J=0.425(10), which separates a first-order transition curve at lower temperatures from a critical second-order transition curve at higher temperatures, in analogy with the previously studied equilibrium Blume-Capel model. Furthermore, we show that, along the second-order transition curve, the critical behavior of the irreversible growth model can be described by means of the critical exponents of the two-dimensional Ising model under equilibrium conditions. Therefore, our findings provide a link between well-known theoretical equilibrium models and nonequilibrium growth processes that are of great interest for many experimental applications, as well as a paradigmatic topic of study in current statistical physics.

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“…Fig. 1 7 ) cm À1 , which are assigned to the B 1(low) , 2B 1(low) , B 1(high) , and TA þ B 1(high) symmetric phonon modes, [11][12][13] respectively. The silent B 1 modes and the second-order modes observed in pure ZnO film are attributed to disorder-activated Raman scattering caused by growth conditions.…”

Section: Methodsmentioning

confidence: 97%

Local vibrational modes competitions in Mn-doped ZnO epitaxial films with tunable ferromagnetism

Cao

Liu

et al. 2014

Journal of Applied Physics

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We reported spectroscopic investigations of high quality Mn-doped ZnO (ZnMnO) films grown by oxygen plasma-assisted molecular beam epitaxy. Raman scattering spectra revealed two local vibrational modes (LVMs) associated with Mn dopants at 523 and 712 cm À1 . The LVMs and magnetic properties of ZnMnO films can be synchronously modulated by post annealing processing or by introducing tiny Co. The relative intensity of two LVMs clearly shows competitions arising from uncompensated acceptor and donor defects competition for ferromagnetic and nonmagnetic films. The experimental results indicated that LVM at 523 cm À1 is attributed to Mn-(Zinc-vacancy) complexes, while LVM at 712 cm À1 is attributed to Mn-(Oxygen-vacancy) complexes. V C 2014 AIP Publishing LLC.

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Magnetic-field-enhanced forbidden modes in Co-doped ZnO thin films revealed by Raman scattering

Cited by 9 publications

References 26 publications

Raman Submicron Spatial Mapping of Individual Mn-doped ZnO Nanorods

Raman Submicron Spatial Mapping of Individual Mn-doped ZnO Nanorods

Far-from-equilibrium growth of magnetic thin films with Blume-Capel impurities

Local vibrational modes competitions in Mn-doped ZnO epitaxial films with tunable ferromagnetism

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