UCL Impact Studentship with the Diamond Light Source by taoyni

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   UCL Impact Studentship with the Diamond Light Source
             Novel X-ray methods for imaging multi-functional materials

                               Professor Des McMorrow
                              London Centre for Nanotechnology


New states of matter emerge when electrons interact strongly in materials. Examples include the
anomalous electron fluid in high-temperature superconductors, Bose-Einstein condensates of
magnons, the Luttinger liquid in one-dimensional conductors, etc. Understanding the properties of
these novel, many-body quantum states represents one of the main intellectual drivers in
contemporary physics, and is essential for establishing new technologies. A key challenge is to
develop experimental methods capable of imaging the electron correlations that endow such quantum
matter with their exceptional properties.

The facilities on the Harwell Science and Innovation Campus (HSIC) are ideally suited to meet this
challenge. Here we propose a collaborative project between the London Centre for Nanotechnology
and the Diamond Light Source that will be targeted at developing novel methods for X-ray imaging
electron correlations in future generations of multi-functional materials.

Research outline
The project will be supervised jointly by Prof. Des McMorrow from the LCN, and Prof. Steve Collins
from Diamond Light Source.

In the first instance the project will build on the success the team has had in recent years in
understanding the properties of multiferroics (see, for example, [1-3]). These are multifunctional
materials that are simultaneously magnetic and ferroelectric and which hold great promise in device
applications. It is expected that the methods developed will have wide range applicability to many
other systems displaying complex/competing order parameters.

The specific aims of the project are:
   • The development of novel X-ray polarization techniques for imaging complex order
       parameters.
   • The application of the polarization techniques in imaging modes, enabling the visualization of
       domains and domain walls.
   • The extension of the above methods to study the in-situ behaviour of domains when
       manipulated with applied magnetic and electric fields.
   • There will also be a major opportunity for the student to produce new software tools required
       for the data analysis.

Experimental studies will be focused on Diamond Beamline I16 (Materials & Magnetism) with the
possibility of visits to other beamlines at Diamond and the ESRF. Beamline I16 is a World-class
diffraction facility which is optimized for studies of resonant and magnetic scattering from complex
materials, and is very well suited to the instrumentation developments envisaged as an essential
aspect of this project, including microfocusing and polarization manipulation.

The student will be expected to spend extended periods at Diamond Light Source so as to be fully
integrated with the research team running the beamline. Experience has shown that this allows the
student to make more rapid progress on a project that would otherwise be the case.
Research impact
Impact will arise from the research project outlined above in several key regards. First, new
techniques arising from the project will have an impact on our understanding of the fundamental
properties of strongly correlated electron systems. This will lead to publications in high-impact journals
(see below for evidence of the combined track record), but will also lay important groundwork for
exploitation of these materials in device applications. The project will also have a positive impact on
UCL’s wider strategic goal of playing a leading role of both the development and exploitation of the
HSIC.

Matching funds
50% matching funds will be provided by Diamond Light Source Ltd. In the context of the Impact
Studentships it is important to note that Diamond Light Source Ltd is a private, joint venture company
funded by the Wellcome Trust and STFC.

Track record
Since joining UCL in 2004 Des McMorrow has supervised four Ph.D. students as principal supervisor,
and the same number as second supervisor. The first of the students for whom he is principal
supervisor, Andrew Walters, submitted his Ph.D. thesis in May 2009, and passed his viva within the
four-year period. He was awarded the Marshall Stoneham prize to the outstanding thesis in
condensed matter physics. Tom Forrest has written his thesis and will submit by the middle of
February 2010, three years four months after starting his Ph.D. Federica Fabrizi is finalizing a draft of
her thesis and will complete three years only at the end of January 2010. The fourth student, Phil
Merchant, started in October 2008 and has made excellent progress.

Prof. Des McMorrow has an outstanding publication record. In the last ten years he has published 20
Physical Review Letters, 4 articles in Nature group journals, 3 in Science and 1 in Proceedings of the
National Academy of Sciences. He has also co-authored one of the standard text books for the
teaching of X-ray physics (“Elements of Modern X-ray Physics”, Wiley, 2001).

Prof. Steve Collins is the Principal Beamline Scientist on the Materials and Magnetism Beamline, I16
at the Diamond Light Source. He has an excellent track record of publishing in high-profile journals
including Physical Review Letters and Nature, and is co-author of text book “X-ray Scattering and
Absorption by Magnetic Materials” (Oxford University Press, 1996), and a contributor to “Magnetism
and Synchrotron Radiation: New Trends” (Springer, 2010).

Departmental support

The project has been discussed with the Head of Department, Gabriel Aeppli, who lends it his full
support.

References
[1] Nature of the magnetic order and origin of induced-ferroelectricity in TbMnO3
S. B. Wilkins, et al. (2009) Phys. Rev. Lett. 103 207602
[2] Circularly polarized X-rays as a probe of non-collinear magnetic order in multiferroic
TbMnO3
F. Fabrizi, et al. (2009) Phys. Rev. Lett. 102 237205
[3] X-ray imaging of the electric field control of multiferroic domains in Ni3V2O8 using
polarization enhanced topography
F. Fabrizi, et al. (2010) Phys. Rev. Lett. (submitted)

								
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