Ferromagnetic Ge1-xMx (M = Mn, Co, and Fe) Nanowires

2007 ◽  
Vol 1032 ◽  
Author(s):  
Yong Jae Cho ◽  
chang hyun Kim ◽  
jeunghee Park
Keyword(s):  
Magnetic Circular Dichroism ◽  
Room Temperature Ferromagnetism ◽  
Cluster Formation ◽  
Magnetization Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Doping ◽  
X Ray Absorption ◽  
Mn Doped ◽  
Fe Ions

AbstractWe synthesized Ge and Ge1-xMx (M = Mn, Co, and Fe, x ≤ 0.2) nanowires using thermal vapour transport method. All nanowires consisted of single-crystalline Ge nanocrystals grown uniformly with the [111] direction. High-resolution X-ray diffraction pattern shows no cluster formation for all Ge1-xMx nanowires. The Mn and Fe doping decreases the lattice constant, but not Co doping. X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurement revealed that the Mn2+ and Fe2+ ions preferentially occupy the tetrahedral sites, substituting for Ge. We suggest that the Mn or Fe ions produce dopant-acceptor hybridization with host defects in p-type Ge, but not Co ions. The magnetic moment of Mn2+ ions reaches a maximum for x = ∼ 0.1, which is much larger than that of the Fe2+ ions. The magnetization measurement also confirms the room-temperature ferromagnetism of Mn-doped Ge nanowires, which is maximized at x = ∼ 0.1. We conclude that the Mn ions are most efficiently doped into the Ge nanowires to form a ferromagnetic semiconductor.

scholarly journals The Study of Magnetic Properties for Non-Magnetic Ions Doped BiFeO3

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4061
Author(s):  
Yongtao Li ◽  
Liqing Liu ◽  
Dehao Wang ◽  
Hongguang Zhang ◽  
Xuemin He ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Local Structure ◽  
Metal Ion ◽  
Single Phase ◽  
Sol Gel ◽  
X Ray ◽  
Co Doping ◽  
Magnetic Ions ◽  
X Ray Absorption ◽  
Fe Ions

BiFeO3 is considered as a single phase multiferroic. However, its magnetism is very weak. We study the magnetic properties of BiFeO3 by Cu and (Cu, Zn). Polycrystalline samples Bi(Fe0.95Cu0.05)O3 and BiFe0.95(Zn0.025Cu0.025)O3 are prepared by the sol-gel method. The magnetic properties of BiFe0.95(Zn0.025Cu0.025)O3 are greater than that of BiFeO3 and Bi(Fe0.95Cu0.05)O3. The analyses of X-ray absorption fine structure data show that the doped Cu atoms well occupy the sites of the Fe atoms. X-ray absorption near edge spectra data confirm that the valence state of Fe ions does not change. Cu and Zn metal ion co-doping has no impact on the local structure of the Fe and Bi atoms. The modification of magnetism by doping Zn can be understood by the view of the occupation site of non-magnetically active Zn2+.

Martensite Transition and Microscopic Magnetism of Epitaxial Ni2MnGa Films

2007 ◽  
Vol 1050 ◽  
Author(s):  
Gerhard Jakob ◽  
Tobias Eichhorn ◽  
Michael Kallmayer ◽  
Hans-Joachim Elmers
Keyword(s):  
Magnetic Circular Dichroism ◽  
Theoretical Calculations ◽  
Magnetic Moments ◽  
Structural Phase ◽  
Absorption Feature ◽  
X Ray Diffraction ◽  
Orbital Contribution ◽  
X Ray ◽  
Transmission Geometry ◽  
X Ray Absorption

AbstractA magnetically induced shape memory effect in Ni2MnGa results in huge magnetostrictive effects of several percent. Using x-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD) we investigated element specific magnetic moments and electronic structure of single crystalline, (110) oriented Ni2MnGa films on a-plane Al2O3 substrates in the austenite and martensite state. The structural phase transition of the samples is evident from temperature dependent x-ray diffraction and magnetization measurements. The Ni XAS differ significantly for temperatures above and below the martensite transition in agreement with published ab-initio calculations. Using XAS in transmission geometry on our thin film samples we observe the corresponding reduction of the absorption feature as predicted by theoretical calculations. The XMCD analysis shows the orbital contribution of the Ni electrons to be responsible for the magnetic anisotropy.

The Structure and Ferromagnetic Properties of the Single Phase Bi0.95Eu0.05Fe0.95Co0.05O3 Nanoparticles Prepared by Sol-Gel

2012 ◽  
Vol 512-515 ◽  
pp. 1434-1437
Author(s):  
Xing Ao Li ◽  
Peng Li ◽  
Yong Tao Li ◽  
Jian Ping Yang ◽  
Qiu Fei Bai ◽  
...  
Keyword(s):  
Single Phase ◽  
Sol Gel ◽  
Mixed Valence ◽  
Magnetic Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Valence States ◽  
Sol Gel Process ◽  
X Ray Absorption ◽  
Fe Ions

Bi0.95Eu0.05Fe0.95Co0.05O3 Nanoparticles sample was prepared by sol-gel process. The microstructure of samples was analysised by X-ray diffraction(XRD), the result indicated that it was the single phase rhombohedral perovskite structure. The morphology of samples was measured by scanning electron microsopy(SEM), the SEM photograph of samples indicated that the nanoparticles of Bi0.95Eu0.05Fe0.95Co0.05O3 sample were small than that of BiFeO3. The valence states of Fe ions in the samples was analysised by the X-ray absorption spectroscopy（XAS）. The XAS of Fe2p showed that it was the mixed valence states (Fe2+ and Fe3+) of Fe ions in samples, and the binding energy of Bi0.95Eu0.05Fe0.95Co0.05O3 was bigger than that of BiFeO3.The magnetic characteristics of the samples were measured by vibrating sample magnetometer (VSM)，the results showed that the weak metamagnetism were obtained from clear hysteresis loop and the magnetic saturation reached 0.408emu/g，compared with BiFeO3 sample, the magnetic properties were significantly enhanced.

STRUCTURE AND MAGNETIC PROPERTIES IN Mn-DOPED Si

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3469-3472 ◽  
Author(s):  
Z. Y. ZHAI ◽  
X. S. WU ◽  
W. ZHANG ◽  
B. QIAN ◽  
Y. M. ZHANG ◽  
...  
Keyword(s):  
Room Temperature ◽  
Annealing Temperature ◽  
Magnetic Circular Dichroism ◽  
X Ray Diffraction ◽  
Si Substrate ◽  
X Ray ◽  
Post Annealing ◽  
Two Phases ◽  
Mn Doped ◽  
Post Annealing Temperature

The composition of Mn 0.05 Si 0.95 polycrystalline films on (001) Si substrate are prepared by vacuum deposition and post-crystallization processes. X-ray diffraction studies indicate that there are two phases coexist in the film: tetragonal, Mn 4 Si 7 and diamond-like Si (Mn) . The content of Si(Mn) phase increases with increasing the post-annealing temperature. Temperature dependence of the magnetization shows that there are two ferromagnetic phases with Curie temperature of around 50 K and near room temperature, which is confirmed by x-ray magnetic circular dichroism (XMCD).

STRUCTURAL AND MAGNETIC PROPERTIES OF NANOCRYSTALLINE Sn0.98Co0.02O2 UNDER DIFFERENT ANNEALING CONDITIONS

2011 ◽  
Vol 10 (01n02) ◽  
pp. 313-317
Author(s):  
SUNITA MOHANTY ◽  
S. RAVI ◽  
H. S. JENA ◽  
V. MANIVANNAN
Keyword(s):  
Single Phase ◽  
Room Temperature Ferromagnetism ◽  
Magnetization Measurement ◽  
Ferromagnetic Behavior ◽  
Magnetic Polaron ◽  
X Ray Diffraction ◽  
Nitrogen Gas ◽  
X Ray ◽  
Annealing Conditions ◽  
Transmission Electron

Nanocrystalline samples of pure and 2 at% Co -doped SnO 2 was prepared by a co-precipitate technique with a crystallite size of the order 10 nm. The homogeneity and single-phase nature of the sample was confirmed by using various characterization techniques, such as X-ray diffraction, transmission electron microscope, and Fourier infrared spectroscopy. Magnetization measurement shows a signature of room temperature ferromagnetism. The reduction in magnetization with decrease in crystalline size has been explained as a result of restriction in the range of bound magnetic polaron interaction. The samples prepared under nitrogen gas environment exhibit improvement in ferromagnetic behavior and enhanced electrical conductivity.

FERROMAGNETISM IN Fe-DOPED ZnO THIN FILMS

2009 ◽  
Vol 23 (06) ◽  
pp. 815-824 ◽  
Author(s):  
R. B. ZHAO ◽  
D. L. HOU ◽  
Y. Y. WEI ◽  
Z. Z. ZHOU ◽  
C. F. PAN ◽  
...  
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Exchange Coupling ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
X Ray Diffraction ◽  
Axis Orientation ◽  
X Ray ◽  
Si Substrates ◽  
Fe Ions

Zn 1-x Fe x O (x = 0.04, 0.06, 0.08, 0.10, 0.12) thin films were grown on Si substrates using reactive magnetron sputtering. X-ray diffraction analyses show that the samples have wurtzite structures with the c-axis orientation. X-ray photoelectron spectroscopy results indicate that the Fe ions are in a +2 charge state in the films. Magnetization measurements indicate that room temperature ferromagnetism is present in films annealed in vacuum while films annealed in air were non-magnetic. The presence of oxygen vacancies in these films may mediate exchange coupling of the dopant ions, resulting in room temperature ferromagnetism.

MICRO-EMULSION METHOD FOR THE SYNTHESIS AND CHARACTERIZATION OF La, Mn-DOPED Ba3Co2 Fe24O41 Z-TYPE HEXA-NANOFERRITES

2019 ◽  
Vol 26 (10) ◽  
pp. 1950065
Author(s):  
GHULAM FARID ◽  
MUHAMMAD SAIF ◽  
GHULAM MURTAZA ◽  
ATIF HUSSAIN ◽  
MUHAMMAD UMAIR ◽  
...  
Keyword(s):  
Hysteresis Loops ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Emulsion Method ◽  
X Ray ◽  
Ion Doping ◽  
Micro Emulsion ◽  
X Ray Absorption ◽  
Mn Doped

In this report, micro-emulsion method was used to obtain La, Mn-doped Ba3Co2 [Formula: see text][Formula: see text] single-phase Z-type hexa-nanoferrites by maintaining annealing temperature at 1200∘C. X-ray diffraction (XRD) analysis shows lattice parameters, crystallite size, and volume are significantly enhanced by introducing La and Mn ions instead of Ba and Fe, respectively. Moreover, La and Mn ion doping improved the preferred orientation of atoms through the basal plane of Z-type hexaferrite. Field emission scanning electron microscopy (FESEM) study reveals that the surface morphology of La- and Mn-doped Ba3Co2 [Formula: see text][Formula: see text], Z-type ferrites show ultrafine and small particle size. The analysis of X-Ray absorption near edge spectroscopy (XANES) suggests that transition in [Formula: see text] has occurred from 3d core level to empty electronic state above the Fermi level. Furthermore, it is observed that in the Z-type ferrites Co exist as divalent ion and Fe as trivalent ion by analyzing XANES. Vibrating samples magnetometer (VSM) indicated that the samples are ferromagnetic as they have narrow hysteresis loops. The decrease in coercivity is due to paramagnetic dopant element Manganese (Mn).

scholarly journals Relevance of the Preparation of the Target for PLD on the Magnetic Properties of Films of Iron-Doped Indium Oxide

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 381 ◽  
Author(s):  
Hasan B. Albargi ◽  
Marzook S. Alshammari ◽  
Kadi Y. Museery ◽  
Steve M. Heald ◽  
Feng-Xian Jiang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Indium Oxide ◽  
Magnetic Circular Dichroism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Saturation Magnetisation ◽  
Fixed Concentration ◽  
Iron Doped ◽  
X Ray Absorption

This paper concerns the importance of the preparation of the targets that may be used for pulsed laser deposition of iron-doped indium oxide films. Targets with a fixed concentration of iron are fabricated from indium oxide and iron metal or one of the oxides of iron, FeO, Fe3O4 and Fe2O3. Films from each target were ablated onto sapphire substrates at the same temperature under different oxygen pressures such that the thickness of the films was kept approximately constant. The films were studied using X-ray diffraction, X-ray absorption (both XANES and EXAFS), optical absorption and magnetic circular dichroism. The magnetic properties were measured with a SQUID magnetometer. At the lowest oxygen pressure, there was evidence that some of the iron ions in the films were in the state Fe2+, rather than Fe3+, and there was also a little metallic iron; these properties were accompanied by a substantial magnetisation. As the amount of the oxygen was increased, the number of defect phases and the saturation magnetisation was reduced and the band gap increased. In each case, we found that the amount of the oxygen that had been included in the target from the precursor added to the effect of adding oxygen in the deposition chamber. It was concluded that the amount of oxygen in the target due to the precursor was an important consideration but not a defining factor in the quality of the films.

scholarly journals Correlation between the green-like coloration and the structural and electronic properties of celadon glazes (I)

Cerâmica ◽  
2012 ◽  
Vol 58 (347) ◽  
pp. 328-337 ◽  
Author(s):  
M. Hidaka ◽  
K. Takeuchi ◽  
R. P. Wijesundera ◽  
L. S. R. Kumara ◽  
M. Watanabe ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Treatment ◽  
Fluorescence Analysis ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural And Electronic Properties ◽  
X Ray Absorption ◽  
Fe Ions

Celadon glazes have been investigated by means of ordinary X-ray fluorescence analysis, and X-ray diffraction and X-ray absorption spectra using synchrotron radiation. The tentative glazes are prepared by mixing raw celadon materials of Masuda feldspar, limestone, quartz, and extra-added Fe2O3 of about 1wt% at thermal treatment till about 1300 °C. It is found that the glaze-colors strongly depend on the Fe2O3 amount and the high-temperature treatment under oxidizing and deoxidizing in the used kiln. Especially, the characteristic color of blue-green, white-green-brown, and white-blue-green result from complex hybridized 3d5L and 3d6L bands. The 3d6L hybridization is induced by an electronic exchange interaction between an empty 3d6 orbital of Fe ions and an occupied 2p orbital of surrounding O ions in the (SiO2 - Al2O3 - CaO) basic complex ceramics of glass-state under the deoxidizing thermal treatment.

scholarly journals Analysis of the halo background in femtosecond slicing experiments

2016 ◽  
Vol 23 (3) ◽  
pp. 700-711 ◽  
Author(s):  
Daniel Schick ◽  
Loïc Le Guyader ◽  
Niko Pontius ◽  
Ilie Radu ◽  
Torsten Kachel ◽  
...  
Keyword(s):  
Magnetic Circular Dichroism ◽  
Analytical Models ◽  
Simplified Model ◽  
Experimental Characterization ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Absorption ◽  
Physical Quantities

The slicing facility FemtoSpeX at BESSY II offers unique opportunities to study photo-induced dynamics on femtosecond time scales by means of X-ray magnetic circular dichroism, resonant and non-resonant X-ray diffraction, and X-ray absorption spectroscopy experiments in the soft X-ray regime. Besides femtosecond X-ray pulses, slicing sources inherently also produce a so-called `halo' background with a different time structure, polarization and pointing. Here a detailed experimental characterization of the halo radiation is presented, and a method is demonstrated for its correct and unambiguous removal from femtosecond time-resolved data using a special laser triggering scheme as well as analytical models. Examples are given for time-resolved measurements with corresponding halo correction, and errors of the relevant physical quantities caused by either neglecting or by applying a simplified model to describe this background are estimated.

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