SUBTLE INTERPLAY BETWEEN HYDROGEN AND MAGNETISM IN Co DOPED ZnO

2012 ◽  
Vol 01 (01) ◽  
pp. 1250001
Author(s):  
Y. B. ZHANG ◽  
M. H. N. ASSADI ◽  
S. LI
Keyword(s):  
Magnetic Properties ◽  
Point Defect ◽  
First Principles ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Strong Tendency ◽  
Doped Zno ◽  
Co Doped

The effects of hydrogen, either interstitial (HI) or substitutional (Ho), on magnetic properties of Co doped ZnO (ZnO:Co) have been systematically investigated using first-principles density functional calculations. The study discovers the correlation between the distribution of Co ions and the hydrogen point defect and magnetism. It is found that Co ions and hydrogen have a strong tendency toward aggregation and hydrogen mainly contributes to the room temperature ferromagnetism observed experimentally in ZnO:Co . Furthermore, in ZnO:Co , the formation of Ho with four-fold hydrogenic bonds is favored over HI by 0.4 eV.

ROOM TEMPERATURE FERROMAGNETISM IN Mn DOPED ZnO SEMICONDUCTOR

2009 ◽  
Vol 23 (08) ◽  
pp. 2029-2040 ◽  
Author(s):  
R. K. SINGHAL ◽  
S. N. DOLIA ◽  
M. S. DHAWAN ◽  
S. K. GAUR ◽  
SUDHISH KUMAR ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Recent Past ◽  
Doped Zno ◽  
Ferromagnetic Ordering ◽  
Mn Doped ◽  
Zno Semiconductor ◽  
Ferromagnetic Contribution ◽  
Co Doped

Following the theoretical prediction of ferromagnetism in Mn - and Co -doped ZnO , there has been an immense experimental search for dilute semiconductors that show ferromagnetic ordering above room temperature, and several workers have reported ferromagnetism in bulk samples as well as in thin films of these materials. Mn -doped ZnO is the key material in this regard, which has been, in the recent past, shown to exhibit such magnetic properties. Many more such attempts have either led to failure or to a much lower Tc, and there have been a lot of confronting reports casting considerable doubts on the magnetism in this system. In order to shed some light, we have prepared and characterized dilute Mn -doped (2 and 4%) ZnO pellets. SQUID measurements confirm that the 2% sample shows above room temperature ferromagnetic ordering, the ferromagnetic contribution coming mainly from the bulk. The ordering gets completely quenched for 4% Mn doping. Upon cooling down, the 2% Mn doped sample showed further enhancement in magnetic properties appreciably. On the other hand, the 4% sample did not show any ferromagnetic ordering, even down to 5 K, and has been found to retain the paramagnetic character.

Hydrogen induced room-temperature ferromagnetism in Co-doped ZnO: first-principles and Monte Carlo study

2014 ◽  
Vol 59 (26) ◽  
pp. 3232-3238 ◽  
Author(s):  
Jian-Min Zhang ◽  
Zhigao Chen ◽  
Kehua Zhong ◽  
Guigui Xu ◽  
Zhigao Huang
Keyword(s):  
Monte Carlo ◽  
First Principles ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Monte Carlo Study ◽  
Doped Zno ◽  
Co Doped

Photoluminescence and Magnetic Properties of Undoped and (Mn, Co) co-doped ZnO Nanoparticles

2020 ◽  
Vol 16 (4) ◽  
pp. 655-666
Author(s):  
Mona Rekaby
Keyword(s):  
Magnetic Properties ◽  
Zno Nanoparticles ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Structural Defects ◽  
Ferromagnetic Behavior ◽  
Secondary Phases ◽  
Antiferromagnetic Ordering ◽  
Doped Zno ◽  
Co Doped

Objective: The influence of Manganese (Mn2+) and Cobalt (Co2+) ions doping on the optical and magnetic properties of ZnO nanoparticles was studied. Methods: Nanoparticle samples of type ZnO, Zn0.97Mn0.03O, Zn0.96Mn0.03Co0.01O, Zn0.95Mn0.03 Co0.02O, Zn0.93Mn0.03Co0.04O, and Zn0.91Mn0.03Co0.06O were synthesized using the wet chemical coprecipitation method. Results: X-ray powder diffraction (XRD) patterns revealed that the prepared samples exhibited a single phase of hexagonal wurtzite structure without any existence of secondary phases. Transmission electron microscope (TEM) images clarified that Co doping at high concentrations has the ability to alter the morphologies of the samples from spherical shaped nanoparticles (NPS) to nanorods (NRs) shaped particles. The different vibrational modes of the prepared samples were analyzed through Fourier transform infrared (FTIR) measurements. The optical characteristics and structural defects of the samples were studied through Photoluminescence (PL) spectroscopy. PL results clarified that Mn2+ and Co2+ doping quenched the recombination of electron-hole pairs and enhanced the number of point defects relative to the undoped ZnO sample. Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM). (Mn, Co) co-doped ZnO samples exhibited a ferromagnetic behavior coupled with paramagnetic and weak diamagnetic contributions. Conclusion: Mn2+ and Co2+ doping enhanced the room temperature Ferromagnetic (RTFM) behavior of ZnO. In addition, the signature for antiferromagnetic ordering between the Co ions was revealed. Moreover, a strong correlation between the magnetic and optical behavior of the (Mn, Co) co-doped ZnO was analyzed.

The Room Temperature Ferromagnetism of (N, Co) Co-Doped ZnO Nanopaticles

2014 ◽  
Vol 577 ◽  
pp. 19-22
Author(s):  
Ping Cao ◽  
Yue Bai ◽  
Zhi Qu
Keyword(s):  
Zno Nanoparticles ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Crystal Lattices ◽  
Grown Sample ◽  
N Doping ◽  
Doped Zno ◽  
Zno Crystal ◽  
Zno Nanopaticles ◽  
Co Doped

Co-doped ZnO nanoparticles were fabricated by an electrodeposition method. The XPS results show Co ions have doped into the ZnO crystal lattices successfully. The as-grown sample has no ferromagnetism at room temperature. But after an ammine plasma treatment the room temperature ferromagnetism were detected on Co0.04Zn0.96O nanoparticles. The Hall measurement reveals after the treatment the resistivity increase by three orders of magnitude. Although the aspect conductivity is n type, some holes generated by N doping play an important role to induce the ferromagnetic properties for Co doped ZnO sample.

First-Principles Study on Co-Doped ZnO with Oxygen Vacancy

2010 ◽  
Vol 154-155 ◽  
pp. 124-129
Author(s):  
Zhen Zhen Weng ◽  
Zhi Gao Huang ◽  
Wen Xiong Lin
Keyword(s):  
Oxygen Vacancy ◽  
First Principles ◽  
Density Functional ◽  
Exchange Interactions ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Ferromagnetic Exchange ◽  
Ferromagnetic Ground State ◽  
Doped Zno ◽  
Co Doped

The interatomic exchange interactions and the electronic structure of Co-doped ZnO with and without oxygen vacancy have been investigated by the first-principles calculations based on density functional theory. It is found that the oxygen vacancy can strengthen the ferromagnetic exchange interaction between Co atoms and might be available for carrier mediation. The oxygen vacancy near to the Co atoms is more favorable for the ferromagnetic ground state.

scholarly journals Doping effect and oxygen defects boost room temperature ferromagnetism of Co-doped ZnO nanoparticles: experimental and theoretical studies

RSC Advances ◽  
2019 ◽  
Vol 9 (40) ◽  
pp. 23012-23020 ◽  
Author(s):  
Yan Zong ◽  
Yong Sun ◽  
Shiyan Meng ◽  
Yajing Wang ◽  
Hongna Xing ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Decomposition Method ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Theoretical Studies ◽  
Thermal Decomposition Method ◽  
Oxygen Defects ◽  
Doped Zno ◽  
Experimental And Theoretical Studies ◽  
Co Doped

Co-doped ZnO nanoparticles with different dosage concentrations were fabricated by a thermal decomposition method.

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