IAEA CRP: Ion Beam Modification of Insulators RCM, Dec. 10-14, 2007, FNRC, Uni. Chiang Mai, Thailand...
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IAEA CRP: Ion Beam Modification of Insulators RCM, Dec. 10-14, 2007, FNRC, Uni. Chiang Mai, Thailand Study of the formation of ferro-, para- and Study of the formation of ferro-, para- and superpara-magnetic nano clusters by ion superpara-magnetic nano clusters by ion implantation itno suitable insulators implantation itno suitable insulators Principal investigators : Prof. K. Bharuth-Ram , University of Principal investigators : Prof. K. Bharuth-Ram , University of KwaZulu-Natal, Durban KwaZulu-Natal, Durban and iThemba LABS, Faure. S. Africa and iThemba LABS, Faure. S. Africa Prof. Dr. Hans Hofsaess, Prof. Dr. Hans Hofsaess, Universitaet Goettingen, Germany Universitaet Goettingen, Germany + Carsten Ronning, Peter Schaaf, Michael + Carsten Ronning, Peter Schaaf, Michael Uhrmacher, Uni-Goettingen. Uhrmacher, Uni-Goettingen. Terry Doyle, Cebo …, iThemba LABS, South Terry Doyle, Cebo …, iThemba LABS, South Africa. Africa.
IAEA CRP: Ion Beam Modification of Insulators RCM, Dec. 10-14, 2007, FNRC, Uni. Chiang Mai, Thailand Study of the formation of ferro-, para- and superpara-
IAEA CRP: Ion Beam Modification of Insulators RCM, Dec. 10-14,
2007, FNRC, Uni. Chiang Mai, Thailand Study of the formation of
ferro-, para- and superpara- magnetic nano clusters by ion
implantation itno suitable insulators Principal investigators :
Prof. K. Bharuth-Ram, University of KwaZulu-Natal, Durban and
iThemba LABS, Faure. S. Africa and iThemba LABS, Faure. S. Africa
Prof. Dr. Hans Hofsaess, Universitaet Goettingen, Germany Prof. Dr.
Hans Hofsaess, Universitaet Goettingen, Germany + Carsten Ronning,
Peter Schaaf, Michael Uhrmacher, Uni-Goettingen. + Carsten Ronning,
Peter Schaaf, Michael Uhrmacher, Uni-Goettingen. Terry Doyle, Cebo
, iThemba LABS, South Africa. Terry Doyle, Cebo , iThemba LABS,
South Africa. + Uli Wahl: Emission channeling + Uli Wahl: Emission
channeling Gerd Weyer et al., MS following Mn57 implantation Gerd
Weyer et al., MS following Mn57 implantation
Slide 2
Introduction Nanoclusters of Fm atoms have high proportion of
surface atoms increase spin magnetic moment towards high spin limit
reduction in effective quenching of the orbital magnetic moment. +
quantum size effects + modified valence electron screening Novel
properties: magnetic moments enhanced by up to 35%
superparamagnetic behaviour in clusters below a critical size
magnetic behaviour in non-FM transition metals Applications in
ultra-high recording magnetic recording media, information and
telecommunications technology. Achieved already by ion implantation
at doses of 10 17 cm -2. - due to accumulation at extended lattice
sites? or diffusion and agglomeration of implanted ions?
Slide 3
Objective: Investigate the implantation parameters required to
achieve magnetic nano-clusters, i.e. energy and dose, sample
temperature and annealing characteristics, Methods include
Temperature dependent Moessbauer spectroscopy and magnetization
measurements, to determine the size of clusters and their magnetic
properties. RBS and Raman Spectrometry, MOKE, UV-VIS Transmission
Spectrometry -- to determine implantation profile and complex
formation in the host matrix.
Slide 4
Reported on in June 2006: Implant of 57 Fe at E = 60 keV, at
Uni-Goettingen to a dose of 5 x 10 15 cm -2. Substrates: 3C-SiC,
CVD diamond, graphite Moessbauer spectroscopy (at UKZN) at RT and
LN2 on 3C-SiC sample: as-implanted sample, and after annealing at
400 C. Moessbauer spectroscopy (at Uni-Goettingen) after annealing
at 600 C VSM on as-implanted and after annealing at 600 C on 3C-SiC
sample MOKE and Raman Spectroscopy on as- implanted and after
annealing at 400 C and 600 C: CVD and 3C-SiC samples
Slide 5
Results: Mossbauer Measurements Mossbauer measurements were
made with a approx. 8 mCi source (30 mCi in May 2003). Each
spectrum at RT, has > 10 million events, accumulated over 4
weeks. At LN2, longer measurement time was required.
Slide 6
MOKE Measurements (Magneto-Optical Kerr Effect) a) As implanted
b) T A = 900 K
Slide 7
VSM Measurements (TB Doyle, UKZN) SiC(Fe) sample, Virgin SiC,
Holder VSM measurements only possible after acquisition of a
bipolar power supply for magnet, obtained in 2005 as donation from
the Alexander von Humboldt Stiftung. Plot shows average of data
collected during many measurements over several months (TB Doyle).
We are at the limit of resolution of the device, but a small
ferromagnetic effect is noticeable.
Slide 8
Raman Spectroscopy a) CVD diamond as-Implanted b) CVD diamond
annealed at 900 K c) 3C-SiC sample annealed at 900K
Slide 9
There is evidence of ferromagnetic and paramagnetic ordering,
but data with better statistics is required. So, Plans for 2007
included: i) obtaining new, stronger Moessbauer Sources (50 mCi)
ii) Increasing the concentration of Fe in the samples, iii)
investigating implantation induced magnetization effects in other
substrates. Early in 2007, enriched 57 Fe pellets were purchased,
and implantation into 3C-SiC, CVD diamond, ZnO, SiO2 and graphite
were undertaken at 60 and 80 keV energy, and up to a fluence of 1 x
10 16 /cm 2 (at Goettingen). Two 50mCi MS sources ordered,
eventually delivered in Oct. 2007 Measurements from end October :
CEMS, TMS.
SAIP 2007 Hyperfine Interactions and Measurables 1. Isomer
Shift 2. Magnetic interaction E mag = - . B E mag = m I. g N. B z =
k ( abs ref )( ), lattice site, charge state 3. Electric Quadrupole
Interaction
Slide 12
RBS Measurements 2 MeV 4 He+ Grazing angle = 10 O
Slide 13
UV-VIS Transmission 1.3C-SiC: virgin and implanted region i) as
implanted, ii) Annealed at 350C. 2. ZnO: Implanted regions i) as
implanted ii) Annealed at 350 C.
Slide 14
3C-SiC 1 x 10 16 /cm 2
Slide 15
SiO 2
Slide 16
ZnO as Impl. T A = 350 C
Slide 17
Moessbauer Measurements 1.CVD Diamond:
Slide 18
Magnetization measurements ??? -- merger of UDW and UN UKZN -
School of Physics (and Fac. of Science) to Westville campus VSM
equipment dismantled and still in boxes!!!
Slide 19
Moessbauer Studies following 57 Mn implantation 57 Mn 57 Co EC
137 keV 14.4 keV, 98 ns 0 CE 57 Fe 5/2 3/2 1. 57 Co source: 30 mCi
+ Typical dose: 5 x 10 14 57 Fe t m ~ 14 days lattice damage 2.
In-beam MS CE and recoil implant 57 Fe* t m ~ 24 36 hrs Dose <
10 10 cm-2. t eff = . 3. 57 Mn* implantation Dose < 10 13 cm-2.
decay 57Fe* E recoil = 40 keV t m ~ 10 min. At ISOLDE, CERN Mass
separated 57 Mn* accelerated to 60 keV, and implanted into sample
held at temp T. 14.4 (+ E) keV gammas detected in PPAC, mounted
directly on to MDU.
Slide 20
Production of radioactive ion beams at ISOLDE, CERN.
Slide 21
Slide 22
3C-SiC
Slide 23
Graphite
Slide 24
Components: S1 : Single line D1: defect doublet Sx1 : sharp FM
sextet Sx2 & Sx3: Broad sextets with Eq interaction. Effect is
reversible. due Fe-V-O complex??
Slide 25
Conclusions 1. The lighter mass substrates ( SiC, SiO 2 ) hold
greater promise. 2. After implantation to a fluence of 1 x 10 16 /
cm 2 indications of magnetically split components in Moessbauer
spectra this fluence gives Moessbauer spectra with acceptable
statistics higher dose implantation with Fe-56 other fm species
(Mn, Co) non-fm species (Na, C)
Slide 26
ACKNOWLEDGEMENTS 1.IAEA Wulf Rosenberg and Francoise Mullhauser
2.Hans Hofsaess, Uli wahl and colleagues in Goettingen 3.Yu
Liangden and FNRC, Chiang Mai University 4.The Group generally.
Thank You