Atom-Probe Tomographic Studies of Thin Films and Multilayers

AbstractThis article reviews investigations of the growth and reactions within thin metal and oxide films using atom-probe tomography. Included in this review are (1) studies of interfacial and growth reactions in magnetoresistive metallic, metal/oxide, and magnetic magnetostrictive multilayers; (2) comparison of selected portions of these results to simulated film growth using molecular dynamics; and (3) study of the origin of room-temperature ferromagnetism in dilute magnetic semiconductors. Information of this type is useful in order to understand the formation and thermal evolution of thin films (and to compare to theory and modeling) and, ultimately, to permit further optimization of devices based on thin films.

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Review on Available Theoretical Models for Room Temperature Ferromagnetism in Dilute Magnetic Semiconductors

Journal of Nano- and Electronic Physics ◽

10.21272/jnep.11(3).03039 ◽

2019 ◽

Vol 11 (3) ◽

pp. 03039-1-03039-3 ◽

Cited By ~ 1

Author(s):

Rana Mukherji ◽

◽

Vishal Mathur ◽

Keyword(s):

Room Temperature ◽

Magnetic Semiconductors ◽

Room Temperature Ferromagnetism ◽

Dilute Magnetic Semiconductors ◽

Theoretical Models

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Room temperature ferromagnetism in III–V and II–IV–V2 dilute magnetic semiconductors

Physica B Condensed Matter ◽

10.1016/j.physb.2005.11.124 ◽

2006 ◽

Vol 374-375 ◽

pp. 430-432 ◽

Cited By ~ 9

Author(s):

V.G. Storchak ◽

D.G. Eshchenko ◽

H. Luetkens ◽

E. Morenzoni ◽

R.L. Lichti ◽

...

Keyword(s):

Room Temperature ◽

Magnetic Semiconductors ◽

Room Temperature Ferromagnetism ◽

Dilute Magnetic Semiconductors

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Seebeck and Spin Seebeck effect in Gd-doped GaN thin films for Thermoelectric Devices and Applications

MRS Proceedings ◽

10.1557/opl.2011.1236 ◽

2011 ◽

Vol 1329 ◽

Author(s):

Bahadir Kucukgok ◽

Liqin Su ◽

Elisa N. Hurwitz ◽

Andrew Melton ◽

Liu Zhiqiang ◽

...

Keyword(s):

Thin Films ◽

Low Power ◽

Room Temperature ◽

Magnetic Semiconductors ◽

Dilute Magnetic Semiconductors ◽

Seebeck Effect ◽

Ferromagnetic Behavior ◽

Successful Development ◽

Spintronic Devices ◽

Spin Seebeck Effect

ABSTRACTGaN-based dilute magnetic semiconductors (DMS) have recently been investigated for use in spintronic devices. In particular, Gd-doped GaN has shown very promising room temperature ferromagnetic behavior and potential for use in spintronics applications. III-Nitride materials have recently had their thermoelectric properties investigated; however this work has not been extended to Nitride-based DMS. Understanding the spin-calorimetric characteristics of GaN-based DMS is important to the successful development of low-power spintronic devices. In this paper the Seebeck and spin-Seebeck effect in MOCVD grown Gd-doped GaN (Gd: GaN) are investigated.

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THE GROWTH AND CHARACTERIZATION OF ROOM TEMPERATURE FERROMAGNETIC WIDEBAND-GAP MATERIALS FOR SPINTRONIC APPLICATIONS

International Journal of High Speed Electronics and Systems ◽

10.1142/s0129156406003825 ◽

2006 ◽

Vol 16 (02) ◽

pp. 515-543

Author(s):

MATTHEW H. KANE ◽

MARTIN STRASSBURG ◽

WILLIAM E. FENWICK ◽

ALI ASGHAR ◽

IAN T. FERGUSON

Keyword(s):

Room Temperature ◽

Magnetic Semiconductors ◽

Room Temperature Ferromagnetism ◽

Dilute Magnetic Semiconductors ◽

Chemical Vapor ◽

Wide Bandgap ◽

Organic Chemical ◽

Ferromagnetic Behavior ◽

Spintronic Devices

Wide-bandgap dilute magnetic semiconductors (DMS), such as transition-metal doped ZnO and GaN , have gained attention for use in spintronic devices because of predictions and experimental reports of room temperature ferromagnetism which may enable their use in spintronic devices. However, there has been some debate over the source of ferromagnetism in these materials. This paper focuses on the high quality growth of wide bandgap DMS, and the characterization of Zn 1-x Mn x O produced by melt-growth techniques and Ga 1-x Mn x N grown by metal organic chemical vapor deposition (MOCVD). High resolution X-ray diffraction results revealed no second phases in either the ZnO crystals or the GaN films. Undoped as-grown, bulk crystals of Zn 1-x Mn x O and Zn 1-x Co x O crystals are shown to be paramagnetic at all temperatures. In contrast, the Ga 1-x Mn x N films showed ferromagnetic behavior at room temperature under optimum growth conditions. Experimental identification of the Mn ion charge state and the presence of bands in the bandgap of GaN are investigated by optical spectroscopy and electron spin paramagnetic resonance (EPR). It is shown that the broadening of states in the Mn 3d shell scaled with Mn concentration, and that optical transitions due to this band correlated with the strong ferromagnetism in these samples. However, this band disappeared with an increase in free electron concentration provided by either annealing or doping. Raman studies of Ga 1-x Mn x N revealed two predominant Mn -related modes featured with increasing concentration, a broad disorder related structure at 300cm-1 and a sharper peak at 669cm-1 This works show that the development of practical ferromagnetic wide bandgap DMS materials for spintronic applications will require both the lattice site introduction of Mn as well as careful control of the background defect concentration to optimize these materials.

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Oxide Dilute Magnetic Semiconductors—Fact or Fiction?

MRS Bulletin ◽

10.1557/mrs2008.225 ◽

2008 ◽

Vol 33 (11) ◽

pp. 1053-1058 ◽

Cited By ~ 137

Author(s):

J.M.D. Coey ◽

S.A. Chambers

Keyword(s):

Thin Films ◽

High Temperature ◽

Magnetic Semiconductors ◽

Bulk Material ◽

Room Temperature Ferromagnetism ◽

Magnetic Moments ◽

Dilute Magnetic Semiconductors ◽

Double Exchange ◽

Secondary Phases ◽

Solid State Mater

AbstractMagnetism in oxides was thought to be well-understood in terms of localized magnetic moments and double-exchange or superexchange rules. This understanding was shaken by the publication of an article in 2001 stating that thin films of anatase TiO2 with only 7 at.% Co substitution had a Curie point in excess of 400 K [Matsumoto et al., Science291, 854 (2001)]. Room-temperature ferromagnetism had previously been predicted for p-type ZnO with 5 at.% Mn [Dietl et al., Science287, 1019 (2000)]. A flood of reports of thin films and nanoparticles of new oxide “dilute magnetic semiconductors” (DMSs) followed, and high-temperature ferromagnetism has been reported for other systems with no 3dcations. The expectation that these materials would find applications in spintronics motivated research in this area. Unfortunately, the data are plagued by instability and a lack of reproducibility. In many cases, the ferromagnetism can be explained by uncontrolled secondary phases; it is absent in well-crystallized films and bulk material. However, it appears that some form of high-temperature ferromagnetism can result from defects present in the oxide films [Coey, Curr. Opin. Solid State Mater. Sci.10, 83 (2007); Chambers, Surf. Sci. Rep.61, 345 (2006)], although they are not DMSs as originally envisaged.

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Magneto-transport Properties of Gd-doped In2O3 Thin Films

MRS Proceedings ◽

10.1557/proc-1032-i06-04 ◽

2007 ◽

Vol 1032 ◽

Cited By ~ 2

Author(s):

Ram Gupta ◽

D. Brown ◽

K. Ghosh ◽

S. R. Mishra ◽

P. K. Kahol

Keyword(s):

Thin Films ◽

Rare Earth ◽

Room Temperature ◽

Magnetic Semiconductors ◽

Dilute Magnetic Semiconductors ◽

Growth Conditions ◽

Electronic Charge ◽

X Ray Diffraction ◽

X Ray ◽

Electro Magnetic

AbstractDilute Magnetic Semiconductors (DMS) are a rare group of promising materials that utilize both the electronic charge - a characteristic of semiconductor materials - and the electronic spin - a characteristic of magnetic materials. Oxide based DMS show promise of ferromagnetism (FM) at room temperature. It has been found that doping metal oxides such as ZnO, TiO2, and In2O3 with magnetic ions such as Fe, Co, Mn, and Cr produces DMS, which exhibit FM above room temperature. In2O3, a transparent opto-electronic material, is an interesting prospect for spintronics due to a unique combination of magnetic, electrical, and optical properties. High quality thin films of rare earth magnetic gadolinium (Gd) doped oxide-based DMS materials have been grown by pulsed laser deposition (PLD) technique on various substrates such as single crystal of sapphire (001) and quartz under suitable growth conditions of substrate temperature and oxygen pressure in the PLD chamber. The effect of rare earth magnetic doping on the structural and electro - magnetic properties of these films has been studied using Raman Spectroscopy, X-Ray Diffraction, Scanning Electron Microscopy, and Magneto - Transport. An X- ray diffraction study reveals that these films are single phase and highly oriented. Characteristic Raman peaks typical of indium oxide are observed at 496 and 627 cm−1. We have observed high magnetoresistance (∼18 %) at a relatively small field of 1.3 Tesla for the films with 10 % gadolinium. A detailed study of temperature and magnetic field dependent resistivity, magnetoresistance, and Hall Effect will be presented.

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Increased room temperature ferromagnetism in Co-doped tetrahedral perovskite niobates

Royal Society Open Science ◽

10.1098/rsos.210121 ◽

2021 ◽

Vol 8 (10) ◽

Author(s):

Yi Zhou ◽

Qing He ◽

Fei Zhou ◽

Xingqi Liao ◽

Yong Liu ◽

...

Keyword(s):

Room Temperature ◽

Magnetic Semiconductors ◽

Room Temperature Ferromagnetism ◽

Dilute Magnetic Semiconductors ◽

Defect Band ◽

Co Doping ◽

Band Absorption ◽

Local Spin Polarization ◽

Curie Temperatures ◽

Co Doped

Dilute magnetic semiconductors (DMSs), such as (In, Mn)As and (Ga, Mn)As prototypes, are limited to III–V semiconductors with Curie temperatures ( T c ) far from room temperature, thereby hindering their wide application. Here, one kind of DMS based on perovskite niobates is reported. BaM x Nb (1− x ) O 3− δ ( M = Fe, Co) powders are prepared by the composite-hydroxide-mediated method. The addition of M elements endows BaM x Nb (1− x ) O 3− δ with local ferromagnetism. The tetragonal BaCo x Nb (1− x ) O 3− δ nanocrystals can be obtained by Co doping, which shows strong saturation magnetization ( M sat ) of 2.22 emu g −1 , a remnant magnetization ( M r ) of 0.084 emu g −1 and a small coercive field ( H c ) of 167.02 Oe at room temperature. The ab initio calculations indicate that Co doping could lead to a 64% local spin polarization at the Fermi level ( E F ) with net spin DOS of 0.89 electrons eV −1 , this result shows the possibility of maintaining strong ferromagnetism at room temperature. In addition, the trade-off effect between the defect band absorption and ferromagnetic properties of BaM x Nb (1− x ) O 3− δ is verified experimentally and theoretically.

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Cu and Co codoping effects on room-temperature ferromagnetism of (Co,Cu):ZnO dilute magnetic semiconductors

Journal of Applied Physics ◽

10.1063/1.3583667 ◽

2011 ◽

Vol 109 (10) ◽

pp. 103705 ◽

Cited By ~ 23

Author(s):

Fengchun Hu ◽

Qinghua Liu ◽

Zhihu Sun ◽

Tao Yao ◽

Zhiyun Pan ◽

...

Keyword(s):

Room Temperature ◽

Magnetic Semiconductors ◽

Room Temperature Ferromagnetism ◽

Dilute Magnetic Semiconductors

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Annealing Temperature Dependent Ferromagnetic Behaviors Observed in Highly Orientated Pure NiO Thin Films

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.602-603.956 ◽

2014 ◽

Vol 602-603 ◽

pp. 956-959

Author(s):

Yu Jun Zhang ◽

Yuan Hua Lin ◽

Ce Wen Nan

Keyword(s):

Thin Films ◽

Room Temperature ◽

Diluted Magnetic Semiconductors ◽

Annealing Temperature ◽

Magnetic Semiconductors ◽

Room Temperature Ferromagnetism ◽

Film Surface ◽

Nickel Metal ◽

Diluted Magnetic ◽

Ferromagnetic Impurity

Transition metal (TM) doped NiO is a promising candidate of p-type oxide diluted magnetic semiconductors (DMSs), which shows obvious room-temperature ferromagnetism. When researching the magnetic properties of DMSs, it is very important to get rid of ferromagnetic impurity phases by optimizing the preparation process. For this purpose, pure NiO thin films have been deposited by a pulsed laser deposition method and annealed by different annealing process. As-deposited or low-temperature annealed films show room-temperature ferromagnetism and high-temperature annealed films are not ferromagnetic. Nickel metal should be the origin of ferromagnetism in these thin films. On the other hand, high annealing temperature influences the microstructure of the film surface a lot. These results show a useful method to eliminate ferromagnetic impurity in NiO thin films and to optimize the preparation parameters of TM doped NiO thin films.

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