Transcript MPRI talk - NECSA - Indico

MATERIALS
PHYSICS RESEARCH
INSTITUTE
WITS UNIVERSITY
Materials research in a country whose
main economy is based on ….Minerals!!!
Some History…
The establishment of the CSIR ~1950.
Prof. Nabarro comes to South Africa – Wits
The present Materials Physics Research Institute …Prof FRN Nabarro as
Director. ….`
originally the mechanical properties of metals,
crystallography and electron microscopy, expanded to encompass nuclear
magnetic and electron spin resonance, low temperature physics, optical
spectroscopy and Mössbauer spectroscopy.
Theoretical solid state physics….
New developments which included ultra-low temperature physics, Brillouin
and Raman laser spectroscopy and photoluminescence, theoretical
studies of phonons and ultrasound, computational physics, non-equilibrium
thermodynamics, magnetism, high pressure physics and …nano-materials.
Nuclear Sciences and Ion Beam Analysis (Channeling, RBS, PIXE, ERDA,
TDPAD, NRA) – Ion Implantation – Diamond Physics
Materials Science and Engineering has
been identified as a University Research
Thrust and Materials Science as a Faculty
of Science Research Thrust.
Centre of Excellence (CoE) for Strong
Materials
Members of the MPRI:
Prof. S. Bhattacharyya
Prof. J.D. Comins FRSSAf MASSAf
Prof. T. Derry
Dr. R. M. Erasmus
Prof. A.G. Every FRSSAf MASSAf
Prof. J M Keartland
Dr B A Mathe
Dr M Mujaji
Prof. D Naidoo
Dr S.R. Naidoo
Prof. E Sideras-Haddad
(Director)
Dr Daniel Wamwangi
Associates:
Professor M J R Hoch
Profesor D S McLachlan
Dr Z Chiguvare
Dr S Shrivastava
Dr B. Mwakikunga (CSIR)
FRSSAf MASSAf
FRSSAf
MPRI Research Activities
•Electronic Structure
•Phase Transitions in Solids
•Magnetic Properties
•Transport properties (at millikelvin temperatures and high
magnetic field and frequencies)
•Elastic properties
•Dynamic properties
•Optical properties
•Structure and Defects in Solids
•Metallic Corrosion
•Nanoscale Physics (nano-electronics, growth of nano-materials)
•Thin film preparation and Crystal growth
•Dielectric properties of composites
•Crystal dislocations
•Extended non-equilibrium thermodynamics
•Interfaces and Interfacial Segregation in Solids
•Mechanical Properties – fracture, hardness, elastic-plastic
properties
•Diamond Physics
•Theoretical studies of phonons and ultrasound
5-Years Review: 2010-2014
165 International Publications in
DoE Recognised Journals
MSc Students
PhD Students
Total Postgraduate Students:
24
28
52
Experimental Facilities
at the MPRI
Prof S Bhattacharyya
Equipment for Quantum Transport measurements
Cryogen-free completely automated physical property measurement system
Experiments and Research Facilities:
(i)
Transport property measurements
(Cryogenic VTI) 350 K - 0.3 K, and
field up to 12 T
(ii) Synthesis of nanocrystalline diamond
films (Hot-filament CVD), multilayered carbon thin films, carbon
nanotubes and nanowires by pulsed
laser ablation assisted CVD
(iii) Characterization of Magnetic
properties in low-dimensional carbon 0-12
T (VSM)
(iv)
Impedance measurement up to 67 GHz in the temperature range
400 K to 4 K and magnetic fields up to 3 T
(v)
Microscopy/spectroscopy (SEM/AFM/STM/Optical/Raman)
(vi) Combined SEM and AFM study
(vii) Fabrication of nanoelectronic devices by e-beam lithography
(viii) Nano-manipulation and in situ transport property measurements
Prof J D Comins – R. Erasmus
Raman and Photoluminescence
Spectroscopy
•Lasers: S-P 8W argon ion
laser; S-P 5W Krypton ion
laser; S-P Tunable dye laser
pumped by S-P 15W argon ion
laser.
•Detectors: Liquid nitrogen
cooled CCD; photomultiplier.
•Confocal Raman
microscope with a computer
controlled scanning stage for
2- and 3-D regions.
•Miniature low and high
temperature
microscope
stages
•Furnace and low temperature cryostat.(4 - 1800 K)
•Electrochemical cell for temperature dependent corrosion studies with insitu Raman studies.
•Diamond anvil cell for high pressure studies.
Prof. D. Comins – B. Mathe
Brillouin Scattering Spectroscopy
Brillouin laser light scattering
determines the elastic
properties of materials in bulk
form, thin films and coatings
as a function of temperature,
pressure, micro-structure,
composition strain.
In order to determine the
frequency spectrum of the
scattered light, a high
resolution and contrast pass
interferometer is used.
The high precision
interferometer mirrors are
electronically stabilised on an
electronically controlled antivibration stage.
Surface Brillouin scattering studies at high pressure have been carried out
using a gem-anvil cell
Spectrophotometer
Cary 500 double beam spectrophotometer.
Wavelength range 185 nm to 3 μm.
Studies of optical absorption, specular and diffuse reflectance of
materials.
Studies of defects as a function of temperature using special cryostats
and heating stages.
Deena Naidoo: Mössbauer Spectroscopy
57Fe and 197Au (gold)
Mössbauer spectroscopy.
Cryogenic facilities for
Mössbauer spectroscopy
experiments down to 4 K.
ISOLDE - CERN
Beamline
(57Mn+/119In* ions)
Implantation
Chamber
Mössbauer
Drive
A beam of radioactive 57Mn+ ions (half-life = 1.5 min) is produced at ISOLDE using 1.4 GeV proton-induced fission
in a UC2 target. Beams of 57Mn+ are accelerated to between 40 and 60 keV and implanted into the samples.
Dr. J. Keartland:
Magnetic resonance spectrometers: EPR and NMR
Bruker Electron Magnetic Resonance
Spectrometer operable in both Continuous
Wave and Pulsed modes. A Continuous Flow
Cryostat enables experiments to be done in
the range 2 K to 300 K. The spectrometer is
being used to characterize diamonds and
nanomaterials.
Pulsed Nuclear Magnetic/Quadrupole
Resonance (NMR/NQR) Spectrometer.
Frequency range: 1 MHz to 200 MHz. Used
to probe materials with a large range of
nuclei. In the picture shown it is operating
in zero field mode (a Nuclear Quadrupole
Experiment). A continuous flow cryostat
allows for low temperature investigations.
Dr Marjorie Mujaji
Equipment for site-selective laser spectroscopy
- 8 K closed cycle cryostat
- dye laser range 630 – 660 nm with DCM dye
- double-grating scanning spectrometer 350 – 900 nm - 15W argon ion laser
- cooled photon counter and photon counting electronics
Atomic Force Microscopy / Scanning
Tunneling Microscopy
Various techniques are available with
these two instruments:
(i) Atomic force microscope
(ii) Scanning tunnelling microscope
(iii) Lateral force microscope
(iv) Force modulation and Phase
modulation microscope
(v) Magnetic force microscope
(vi) Electric-field gradient
microscope
(vii) Scanning capacitance
microscope
ACCELERATOR MASS SPECTROMETRY - AMS
Measurements of isotopic ratios
As low as …. 10-15 !!!
10Be, 14C, 27Al, 36Cl, 41Ca
…..Actinides
Ion Implantation
iThemba LABS / WITS
• The future of materials research is unlimited: New terrific opportunities
in novel materials enabled by our recent ability to manipulate matter
at the atomic and molecular scales.
• The birth of nanomaterials and nanoscience
• This size scale, which is about the same as that of biological
structures, opens up a whole new world at the interface of materials
and life sciences.
MRAM chips represent one class of
spintronics, in which the spins of large
numbers of electrons are aligned the same
way, as with a collection of toy tops all
spinning clockwise on the floor.
These so-called spin-polarized electrons typically flow through some part
of the device, forming a spin-polarized current like a polarized beam of
light.
A second class of spintronics: Quantum Spintronics,
manipulation of individual electrons to exploit the quantum
properties of spin.
Quantum Spintronics could provide a practical way to carry out
quantum information processing, which replaces the definite 0s
and 1s of ordinary computing with quantum bits, or qubits,
capable of being 0 and 1 simultaneously, a condition called a
quantum superposition.