scholarly journals Ferromagnetism from non-magnetic ions: Ag-doped ZnO

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nasir Ali ◽  
Vijaya A. R. ◽  
Zaheer Ahmed Khan ◽  
Kartick Tarafder ◽  
Anuvesh Kumar ◽  
...  
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Magnetic Coupling ◽  
Ferromagnetic State ◽  
Coupling Energy ◽  
Unpaired Spin ◽  
Magnetic Ions ◽  
Doped Zno ◽  
Ferromagnetic Ordering ◽  
Magnetic Ion

AbstractTo develop suitable ferromagnetic oxides with Curie temperature (TC) at or above room temperature for spintronic applications, a great deal of research in doping ZnO with magnetic ions is being carried out over last decade. As the experimental results on magnetic ions doped ZnO are highly confused and controversial, we have investigated ferromagnetism in non-magnetic ion, Ag, doped ZnO. When Ag replaces Zn in ZnO, it adopts 4d9 configuration for Ag2+ which has single unpaired spin and suitable exchange interaction among these spins gives rise to ferromagnetism in ZnO with above room temperature TC. Experimentally, we have observed room temperature ferromagnetism (RTFM) in Ag-doped ZnO with Ag concentration varied from 0.03% to 10.0%. It is shown that zinc vacancy (VZn) enhances the ferromagnetic ordering (FMO) while oxygen vacancy (VO) retards the ferromagnetism in Ag-doped ZnO. Furthermore, the theoretical investigation revealed that VZn along with Ag2+ ions play a pivotal role for RTFM in Ag-doped ZnO. The Ag2+-Ag2+ interaction is ferromagnetic in the same Zn plane whereas anti-ferromagnetic in different Zn planes. The presence of VZn changes the anti-ferromagnetic to ferromagnetic state with a magnetic coupling energy of 37 meV. Finally, it has been established that the overlapping of bound magnetic polarons is responsible for RTFM in low doping concentration. However, anti-ferromagnetic coupling sets in at higher doping concentrations and hence weakens the FMO to a large extent.

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.

scholarly journals Magnetic critical behavior of the van der Waals Fe5GeTe2 crystal with near room temperature ferromagnetism

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhengxian Li ◽  
Wei Xia ◽  
Hao Su ◽  
Zhenhai Yu ◽  
Yunpeng Fu ◽  
...  
Keyword(s):  
Critical Behavior ◽  
Critical Exponents ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Van Der Waals ◽  
Three Dimensional ◽  
Magnetic Coupling ◽  
Magnetic Exchange ◽  
Ferromagnetic Exchange ◽  
Ferromagnetic Ordering

Abstract The van der Waals ferromagnet Fe5GeTe2 has a Curie temperature TC of about 270 K, which is tunable through controlling the Fe deficiency content and can even reach above room temperature. To achieve insights into its ferromagnetic exchange that gives the high TC, the critical behavior has been investigated by measuring the magnetization in Fe5GeTe2 crystal around the ferromagnetic ordering temperature. The analysis of the measured magnetization by using various techniques harmonically reached to a set of reliable critical exponents with TC = 273.7 K, β = 0.3457 ± 0.001, γ = 1.40617 ± 0.003, and δ = 5.021 ± 0.001. By comparing these critical exponents with those predicted by various models, it seems that the magnetic properties of Fe5GeTe2 could be interpreted by a three-dimensional magnetic exchange with the exchange distance decaying as J(r) ≈ r−4.916, close to that of a three-dimensional Heisenberg model with long-range magnetic coupling.

Room temperature ferromagnetism in Sb doped ZnO

2021 ◽  
Vol 529 ◽  
pp. 167908
Author(s):  
Cai-Qin Luo ◽  
Si-Cong Zhu ◽  
Chi Xu ◽  
Shengqiang Zhou ◽  
Chi-Hang Lam ◽  
...  
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Doped Zno

Robust Room-Temperature Ferromagnetism with Giant Anisotropy in Nd-Doped ZnO Nanowire Arrays

Nano Letters ◽  
2012 ◽  
Vol 12 (8) ◽  
pp. 3994-4000 ◽  
Author(s):  
Dandan Wang ◽  
Qian Chen ◽  
Guozhong Xing ◽  
Jiabao Yi ◽  
Saidur Rahman Bakaul ◽  
...  
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Nanowire Arrays ◽  
Zno Nanowire ◽  
Zno Nanowire Arrays ◽  
Doped Zno

Effect of defects on room-temperature ferromagnetism of Cr-doped ZnO films

2009 ◽  
Vol 60 (4) ◽  
pp. 214-217 ◽  
Author(s):  
L.J. Zhuge ◽  
X.M. Wu ◽  
Z.F. Wu ◽  
X.M. Chen ◽  
Y.D. Meng
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Zno Films ◽  
Doped Zno

scholarly journals Surfactant-Assisted Synthesis of Co- and Li-Doped ZnO Nanocrystalline Samples Showing Room-Temperature Ferromagnetism

2006 ◽  
Vol 18 (14) ◽  
pp. 1857-1860 ◽  
Author(s):  
O. D. Jayakumar ◽  
I. K. Gopalakrishnan ◽  
S. K. Kulshreshtha
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Doped Zno ◽  
Surfactant Assisted

scholarly journals Intrinsic room temperature ferromagnetism in boron-doped ZnO

2010 ◽  
Vol 97 (23) ◽  
pp. 232502 ◽  
Author(s):  
X. G. Xu ◽  
H. L. Yang ◽  
Y. Wu ◽  
D. L. Zhang ◽  
S. Z. Wu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Boron Doped ◽  
Doped Zno
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