Suppression of Ferromagnetic Ordering in thicker co-sputtered Mn doped MgO Films

2013 ◽  
Vol 1552 ◽  
pp. 83-88 ◽  
Author(s):  
Sreekanth K. Mahadeva ◽  
Zhi-Yong Quan ◽  
J. C. Fan ◽  
K. S. Sreelatha ◽  
L. Belova ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Film Thickness ◽  
Saturation Magnetization ◽  
Room Temperature ◽  
Structural Surface ◽  
Ferromagnetic Ordering ◽  
Surface Morphologies ◽  
Mn Doped ◽  
Different Thickness

ABSTRACTWe report on preliminary studies of low (14 at.%) and high (53at.%) concentration Mn doped MgO films deposited by co-sputtering from metallic Mn and Mg targets. The structural, surface morphologies and magnetic properties of the films of different thickness were studied. All the as grown films are found to be amorphous and film surfaces are found to be flawless and homogeneous. We observe at room temperature robust ferromagnetic loops with a saturation magnetization value that is a function of film thickness reaching a maximum of ∼38.5 emu/cm3 in the Mn0.53Mg0.47O film at a thickness of ∼92 nm. In thicker films room-temperature ferromagnetic ordering is suppressed and eventually at a thickness around 120nm the expected diamagnetism of the bulk appears. The origin of ferromagnetism may be attributed to cation defects at the Mg-site.

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.

On the defect induced ferromagnetic ordering above room-temperature in undoped and Mn doped ZnO thin films

2009 ◽  
Vol 1183 ◽  
Author(s):  
Mukes Kapilashrami ◽  
Jun Xu ◽  
Valter Ström ◽  
K V Rao ◽  
Lyubov Belova
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Room Temperature ◽  
Unit Cell ◽  
Zno Thin Films ◽  
Intrinsic Defect ◽  
Magnetic Elements ◽  
Doped Zno ◽  
Ferromagnetic Ordering ◽  
Mn Doped

AbstractEvidence for long range ferromagnetic order above room-temperature, RTFM, in pristine ZnO, In2O3, TiO2 nanoparticles and thin films, containing no nominal magnetic elements have been reported recently. This could question the origin of RTFM in doped dilute alloys if for example the ZnO matrix itself develops a defect induced magnetic order with a significant moment per unit cell. In this presentation we report a systematic study of the film thickness dependence of RTFM in pure ZnO deposited by DC Magnetron Sputtering. We observe a maximum in the saturation magnetization, MS, value of 0.62 emu/g (0,018 μB/unit cell), for a ˜480 nm film deposited in an oxygen ambience of appropriate pressure. Above a thickness of around 1 μm the films are diamagnetic as expected. We thus see a sequential transition from ferromagnetism to para- and eventual diamagnetism as a function of film thickness in ZnO. We also find that in such a ZnO matrix with a maximum intrinsic defect induced moment, on doping with Mn the maximum enhanced MS value of 0.78 emu/g is obtained for 1at.% Mn doping. With this approach of appropriate doping in a defect tailored matrix, we routinely obtain RTFM in both undoped and Mn- doped ZnO thin films.

The Structure and Magnetic Properties of NiZn-Ferrite Films Deposited by Magnetron Sputtering at Room Temperature

2013 ◽  
Vol 690-693 ◽  
pp. 1702-1706 ◽  
Author(s):  
Shuang Jun Nie ◽  
Hao Geng ◽  
Jun Bao Wang ◽  
Lai Sen Wang ◽  
Zhen Wei Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Magnetron Sputtering ◽  
Saturation Magnetization ◽  
Room Temperature ◽  
Oxygen Flow ◽  
Flow Ratio ◽  
Study Results ◽  
Ferrite Thin Films ◽  
Ferrite Films

NiZn-ferrite thin films were deposited onto silicon and glass substrates by radio frequency magnetron sputtering at room temperature. The effects of the relative oxygen flow ratio on the structure and magnetic properties of the thin films were investigated. The study results reveal that the films deposited under higher relative oxygen flow ratio show a better crystallinity. Static magnetic measurement results indicated that the saturation magnetization of the films was greatly affected by the crystallinity, grain dimension, and cation distribution in the NiZn-ferrite films. The NiZn-ferrite thin films with a maximum saturation magnetization of 151 emucm-3, which is about 40% of the bulk NiZn ferrite, was obtained under relative oxygen flow ratio of 60%.

Growth Peculiarities and Magnetic Properties of (LuBi)3Fe5O12 Films by LPE Method

2013 ◽  
Vol 200 ◽  
pp. 256-260 ◽  
Author(s):  
I.I. Syvorotka ◽  
Igor M. Syvorotka ◽  
S.B. Ubizskii
Keyword(s):  
Magnetic Properties ◽  
Liquid Phase ◽  
Surface Morphology ◽  
Film Thickness ◽  
Faraday Rotation ◽  
Liquid Phase Epitaxy ◽  
Magnetization Reversal ◽  
Room Temperature ◽  
Mirror Surface ◽  
Different Types

The series of (LuBi)3Fe5O12 film were grown on (111) oriented GGG substrate with diameters 1, 2 and 3 inch by liquid phase epitaxy using Bi2O3-base flux. Different types of surface morphology on the grown films were observed. The films’ surface was smooth and mirror while the film thickness was less than 13 μm and becomes rough for thickness above this value. The grown films were characterized by measuring magnetization loops and magneto-optic Faraday rotation under magnetization reversal as well as ferromagnetic resonance (FMR). All films with mirror surface demonstrate the in-plane magnetization, high Faraday rotation and FMR linewidth about 0.8 Oe at 9.1 GHz and room temperature.

Synthesis of Undoped and Manganese-Doped HgTe Nanoparticles Using [Hg(TeCH2CH2NMe2)2] as a Single Source Precursor

2008 ◽  
Vol 8 (9) ◽  
pp. 4500-4505 ◽  
Author(s):  
Gotluru Kedarnath ◽  
Sandip Dey ◽  
Vimal K. Jain ◽  
Gautam K. Dey ◽  
Ramakant M. Kadam
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Lattice Parameter ◽  
Crystalline Solid ◽  
Single Source ◽  
Epr Spectrum ◽  
Single Source Precursor ◽  
Ferromagnetic Ordering ◽  
Mn Doped

The Reaction of [HgCl2(tmeda)] with NaTeCH2CH2NMe2 gave a mercury tellurolate, [Hg(TeCH2CH2·NMe2)2] (1) as a yellow crystalline solid, which was characterized by elemental analysis, UV-vis, mass and NMR (1H, 13C, 125Te, 199Hg) spectroscopy. Thermolysis of 1 in hexadecylamine (HDA) at 90 °C in the absence and presence of Mn(OAc)2·4H2O gave undoped and Mn-doped HgTe nanoparticles which were characterized by XRD, EDAX, TEM, EPR and magnetic measurements. These particles could be synthesized with mean particle size of 6–7 nm (from TEM). Manganese substitution at Hg site in HgTe lead to a linear decrease in lattice parameter with increasing concentration of Mn. Magnetization measurements showed ferromagnetic ordering at room temperature with very small coercive field (Hc, 50 Oe) for Hg0.973Mn0.027 Te sample. This sample also exhibited distinct ferromagnetic resonance (FMR) in the EPR spectrum.

The oxidation behavior and magnetic properties of iron carbonitride ultrafine particles

1996 ◽  
Vol 11 (11) ◽  
pp. 2689-2692
Author(s):  
X. Q. Zhao ◽  
Y. Liang ◽  
Z. Q. Hu ◽  
B. X. Liu
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Ultrafine Particles ◽  
Carbon Coating ◽  
Oxidation Behavior ◽  
Structural Characteristics ◽  
Iron Nitride ◽  
Thin Carbon ◽  
Surface Morphologies

Iron nitride and iron carbonitride (ICN) ultrafine particles (20–80 nm in size) have been synthesized by laser-induced pyrolysis of the Fe(CO)5–NH3–C2H4 system. The oxidation behavior, surface morphologies, and structural characteristics as well as magnetic properties of these particles are reported and discussed. It is found that the presence of very thin carbon coating (1–2 nm) on the ICN particles plays an important role in preventing the oxidation of the particles. Accordingly, the ICN ultrafine particles exhibit higher saturation magnetization (142 emu/g) than the iron nitride ones (124 emu/g).

scholarly journals Magnetic Properties of FePt Nanoparticles Prepared by Sonoelectrodeposition

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Nguyen Hoang Nam ◽  
Nguyen Thi Thanh Van ◽  
Nguyen Dang Phu ◽  
Tran Thi Hong ◽  
Nguyen Hoang Hai ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Metallic Nanoparticles ◽  
Room Temperature ◽  
Cathode Surface ◽  
High Coercivity ◽  
Fept Nanoparticles ◽  
Promising Technique ◽  
Structural And Magnetic Properties

Sonoelectrodeposition is a useful technique to make metallic nanoparticles, using ultrasound during electrodeposition to remove nanoparticles as they grow on the cathode surface. This paper reports some structural and magnetic properties of FePt nanoparticles prepared by this method. The as-prepared Fe45Pt55nanoparticles were ferromagnetic at room temperature. Upon annealing at 700°C for 1 h under H2atmosphere, the saturation magnetization and the coercivity of the nanoparticles were improved significantly. The annealed nanoparticles showed a high coercivity of 13.5 kOe at 2 K and of 9 kOe at room temperature. Sonoelectrodeposition is a promising technique to make large quantity of FePt nanoparticles.

Novel Room-temperature Ferromagnetic Semiconductors Pb1-x-yCaxCryTe

2009 ◽  
Vol 1183 ◽  
Author(s):  
Evgeny P. Skipetrov ◽  
Elena A. Zvereva ◽  
Nikolay A. Pichugin ◽  
Alexey E. Primenko ◽  
Evgeny I. Slyn'ko ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Room Temperature ◽  
Diluted Magnetic Semiconductors ◽  
Magnetic Semiconductors ◽  
Impurity Level ◽  
Ferromagnetic Semiconductors ◽  
Magnetization Curves ◽  
Diluted Magnetic ◽  
Ferromagnetic Ordering

Abstract The galvanomagnetic and magnetic properties of novel diluted magnetic semiconductors Pb1-x-yCaxCryTe (x=0.06-0.20, y=0.003-0.045) have been investigated. Temperature dependencies of the resistivity and the Hall coefficient have a metallic character indicating the pinning of Fermi level by the chromium impurity level on the background of the conduction band states. Magnetization curves display a clear hysteresis loop over the whole temperature range investigated. The Curie temperature, determined from the temperature dependencies of magnetization, achieves 345 K. Possible mechanisms of ferromagnetic ordering were discussed.

A novel recipe to improve the magnetic properties of Mn doped CeO 2 as a room temperature ferromagnetic diluted metal oxide

2014 ◽  
Vol 360 ◽  
pp. 73-79 ◽  
Author(s):  
Faisal A. Al-Agel ◽  
Esam Al-Arfaj ◽  
Ahmed A. Al-Ghamdi ◽  
Yaroslav Losovyj ◽  
Lyudmila M. Bronstein ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Metal Oxide ◽  
Room Temperature ◽  
Mn Doped

scholarly journals Co-Substitution Effect in Room-Temperature Ferromagnetic Oxide Sr3.1Y0.9Co4O10.5

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2301
Author(s):  
Akihiro Tsuruta ◽  
Shuji Kawasaki ◽  
Masashi Mikami ◽  
Yoshiaki Kinemuchi ◽  
Yoshitake Masuda ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
High Spin ◽  
Spin State ◽  
Room Temperature ◽  
High Spin State ◽  
Substitution Effect ◽  
Co Substitution ◽  
Intermediate Spin ◽  
Intermediate Spin State

We investigated the Co substitution effect for the magnetic properties in room-temperature ferromagnetic oxide Sr3.1Y0.9Co4O10.5. The substituted element (Al and Ga) and low-spin state Co3+, which was changed from a high-spin or intermediate-spin state by Al or Ga substitution, reduced the Curie temperature to even 1.5 times lower than the temperature estimated from a simple dilution effect. Al3+ preferentially substituted for intermediate-spin-state Co3+ in the ferrimagnetic CoO6 layer and deteriorated the saturation magnetization of Sr3.1Y0.9Co4O10.5. By contrast, Ga3+ substituted for high-spin-state Co3+ in the CoO6 layer and/or the antiferromagnetic CoO4.25 layer and enhanced the saturation magnetization per Co ion. These results indicate that the magnetic properties of Sr3.1Y0.9Co4O10.5 can be controlled by selectively substituting for Co3+ with different spin states.

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