Nano Engineering & Storage Technology Research Group

Opportunities

The Nano Engineering & Storage Technology (NEST) group has interests predominantly in areas of magnetic data storage, fundamental magnetism, sensors, and graphene. If you are a student interested in PhD studies within our group, or a postgraduate looking for a position within our group, then current opportunities are listed for

 


 

PhD Study

We encourage prospective PhD students to contact us regarding our work and to enquire about PhD projects within the group. We welcome students with any scientific/mathematical background (Physics, Engineering, Computer Science, Mathematics, Chemistry etc) - you do necessarily need a background in nanotechnology and magnetics to succeed within the group.

Funding

PhD studentships are often available from a number of sources including:

These awards cover tuition fees and provide a contribution to living expenses for home students. These are also potentially available for international students.

The group is heavily involved with the NOWNANO DTC: The North West Nanoscience Doctoral Training Centre, through managment of the programme and teaching on the taught element of the programme. Consequently, we offer collaborative research projects to students enrolled on the Nownano DTC.

Projects

Current PhD projects available:

If you are interested in applying for any of the above projects then advice on applying for PhD positions in the School can be found here. You can obtain further information by contacting the named supervisor.


 

Research Positions

We do not currently have any research positions at this time, but please check regularly for updates.

Any new positions will be announced here and advertised on www.jobs.ac.uk.

 


PhD Research Projects

You can find more detailed information about the PhD projects we currently offer below.

Nanofabrication of advanced magnetic structures for data storage applications

Supervisors: Dr Paul Nutter & Dr Ernie Hill

Example of BPMOne major commercial application for the fabrication of nanoscale magnetic structures is in magnetic data storage. The now ubiquitous hard disk drive (HDD) has been one of the greatest technological achievements of the past half-century, with the growth of the storage capacity of HDDs being achieved by scientific advancements, such as the introduction of GMR heads, which won the 2007 Nobel Prize for Physics. However, it is widely accepted that current approaches will fail to deliver the storage capacities required by tomorrow’s technologies. How will they implement a 10TB hard disc drive?

The use of bit-patterned media (BPM) is seen as one solution to this problem, whereby a single data bit is stored to a single magnetically isolated element. The challenge in developing BPM lies in the fabrication of island arrays at dimensions close to the limits of today’s lithographic approaches (1Tbit/in2 requires islands to be spaced on a 25nm x 25nm lattice with islands <20nm in diameter). Island arrays have been successfully produced at densities approaching 1Tbit/in2 by etching continuous films into islands or by depositing films onto pre-patterned substrates, however, the resulting nanostructures have a large variation in structural and magnetic properties that makes them unattractive for use in BPM. To enable the commercial realisation of BPM these variations must be controlled.

The challenging aim of this project is to produce patterned magnetic nanostructures with controlled properties for us in future BPM systems, through the development of novel media and fabrication processes. The project will involve the use of thin film fabrication and materials processing techniques that will push the limits of the nanolithography facilities available in the Manchester Centre for Mesoscience and Nanotechnology. A background in nanotechnology is not necessary for this project. The skills developed are essential for the development of any nanotechnologist and are applicable to nanofabrication in areas outside of data storage.

If you are interested in appling for this project, please contact one of the named supervisors.

Studies of patterned magnetic nanostructures for advanced data storage applications

Supervisors: Dr Paul Nutter & Prof Tom Thomson

MOKE Image of Recorded Bits

Why are we interested in magnetic nanostructures? Because they have many applications, particularly in the development of the next generation of magnetic hard disc drive - the central data storage component in every computer. It is important that the magnetic behaviour of these very small structures (of the order of 1/5000th the width of a human hair) is understood, and to some degree controlled, to enable the development of future mass storage systems.

The magneto-optical Kerr effect (MOKE) is a powerful tool that is used to characterise magnetic materials for a variety of applications, in particular novel magnetic data storage media. The MOKE signal is characterised by the rotation in the plane of polarisation of linearly polarised light upon interaction with a magnetic material. In the case where the magnetisation of the material is perpendicular to its plane then we have the polar MOKE configuration, and the sign and magnitude of the rotation, which is generally very small, is proportional to the magnetisation and its direction. By measuring the MOKE signal in the presence of a variable external field, valuable information about the magnetic properties of the media may be ascertained, such as the coercivity and remanent magnetisation. However, in the case of nanostructured magnetic media, such as that proposed for use in future ultra-high density magnetic hard disk drives, studies have shown that the MOKE signal behaves differently in the regime where the size of the nanostructures is much less than the wavelength of light used.

The objective of this project is to build a MOKE system that will allow the investigation of the physical origins of the variation in MOKE signal observed in the exciting regime where the size of the magnetic nanostructures are much less than the wavelength of light. In particular, the design of this novel instrument will focus on being able to characterise magnetic nanostructures at a variable field angle as well as different wavelengths of illumination, this will allow us to ascertain more of an understanding of the interactions of light with magnetic nanostructures. The project will involve the development of instrumentation as well as the nanoscale patterning of magnetic materials for data storage applications. The project will enable the development of skills in designing and building optical and electronic instrumentation, as well as the opportunity to develop essential skills in nanofabrication.

If you are interested in appling for this project, please contact one of the named supervisors.

Signal evaluation and data recovery in future ultra-high density hard disk drives

Supervisor: Dr Paul Nutter

Media Geometry in BPM

1TB hard disc drives (HDDs) - that is 1,000,000,000,000 byte - are now commonplace and relatively inexpensive. Such high storage capacities have been permitted through the continued development of magnetic recording media, and sensor technology to allow very high storage densities (current HDDs have a storage densities of around 360Gbit/in2). The increasing demand for higher storage capacities in hard disc drives (HDD) will require a future storage density in excess of 1Tbit/in2. However, limitations with current approaches to magnetic data storage will limit the future growth of the storage density of magnetic HDDs.

One exciting technique that is believed will enable the development of HDDs with storage densities in excess of 1Tbit/in2 is the use of bit patterned media (BPM). In BPM each bit is recorded to a nanostructured, isolated, single-domain magnetic island. However, there are a number of problems that prevent the commercial realisation of a HDD product incorporating BPM, most notably the variations in physical island properties, such as position and size, as well as magnetic properties. The effect of these variations is the introduction of errors when recording and reading data. On the whole such variations are unavoidable, although by careful design and fabrication they may be controlled. Understanding how these variations affect the ability to record and recover data is of prime importance to the development of any future HDD technology employing BPM.

We have developed a model of the data recovery process in a BPM storage system, written in the Matlab environment, which allows us to predict how variations in island geometry, in particular variations in island size and position, affect the recovery of data using a standard partial response maximum likelihood (PRML) read channel. The challenge of this project is to expand this work to enable the further investigation of the effect of imperfect media on the recovery of stored data. The project will involve the development of extensive simulations to extend the simulation capabilities of the existing software, including the realistic introduction of micromagnetic variations in island magnetisation, to produce a unique and powerful replay model that will enable accurate predictions of the ability to recover data in a BPM system. The modelling and signal processing skills developed as part of this project are pertinent to other fields, for example communications.

If you are interested in appling for this project, please contact the named supervisor.

Characterisation of nanomagnets for ultra-high density storage applications

Supervisor: Dr Paul Nutter

Hall Cross with BPMNovel nanomagnetic materials are being investigated for a wide variety of applications, in particular in future data storage devices. The growth in the storage capacity of the ubiquitous hard disk drive (HDD) has been extraordinary and has been achieved by the miniaturisation of components (the read/write head geometry, media thickness, grain diameter) and the development of novel recording media. However, problems with thermal instabilities will limit the storage density to approx. 1Tb/in2 using current approaches, so a paradigm shift is required to enable continued growth. The use of bit-patterned media (BPM) is seen as one solution to this problem, whereby a single bit is stored on a single magnetically isolated nano-sized magnetic island.

The exciting challenge in developing BPM lies in the fabrication of island arrays, with uniform island properties, at dimensions close to the limits of today’s lithographic approaches (1Tbit/in2 requires islands to be spaced on a 25nm x 25nm lattice). It is therefore vital that the magnetic properties of fabricated nanostructures are fully understood, since studies have shown that the reduction of island dimensions leads to an undesirable variation in the magnetic field required to switch individual islands.

The challenging aim of this project is to characterise the magnetic behaviour of fabricated structures using the anomalous Hall effect (AHE). The AHE is a very sensitive technique that makes it possible to distinguish the switching of individual magnetic nanostructures as an external field is applied. In order to use the AHE a Hall cross structure must be etched into the sample to act as a current guide and allow the characteristic Hall voltage to be measured. Figure 1 illustrates a sample cross structure containing an array of magnetic nanostructures, fabricated using the extensive nanofabrication facilities available in the group. This project will involve the fabrication of such structures to enable the switching behaviour of magnetic nanostructures to be investigated so that we can develop new media with controlled characteristics for future HDDs. The fabrication skills developed are applicable to all areas of nanofabrication.

If you are interested in appling for this project, please contact the named supervisor.

Graphene Memory Devices

Supervisor: Dr Ernie Hill

Graphene is a two dimensional material consisting of a honeycomb pattern of carbon atoms first fabricated in Manchester University in 2004. It has remarkable electronic properties and could well replace Silicon in memory and processor devices as device dimensions drop below 10 nm. This project will explore the potential of this amazing material for the fabrication of non-volatile memory devices. The student will work along-side research activity into storage technology within the Nano Engineering & Storage Technologies Research Group (http://intranet.cs.man.ac.uk/nest/) and join with the large research activity into the properties and applications of Graphene in the Manchester Centre for Mesoscience & Nanotechnology (http://intranet.cs.man.ac.uk/nanotechnology/).

There are also openings for experimental projects in this area from the nanoengineering of novel graphene memory devices to the development of advanced measurement instruments to determine performance of graphene based nano-storage materials and devices. Projects in this area would mainly suit applied physicists, materials scientists and electronic engineers. Contact e.w.hill@manchester.ac.uk for further details of possible projects.

If you are interested in appling for this project, please contact the named supervisor.

Modelling and fabrication of nanostructured surface in polymer materials

Supervisor: Dr Ernie Hill

There is currently much interest in the replication of nanoscale structures in polymer materials, both for nanoscale device fabrication and for producing templates for cell growth studies in biological systems. This project involves finding ways to characterize and model complex 3D structures which can subsequently be fabricated in a polymer film using electron beam lithography. This work will be carried out in the Center for Mesoscience and Nanotechnology (CMN) with the aim of modeling and then generating a set of well-characterized surface topographies in a polymer substrate having arrays of features covering a broad range of spatial dimensions from several micrometers down to approximately 10 nm in size.

The work will feed into two major areas of research interest. One is on the fabrication of nanoscale devices for memory applications in the Nano Engineering & Storage Technologies Research Group (http://intranet.cs.man.ac.uk/nest/) and the other is into cell growth on polymer surfaces for the prevention of breast capsular contracture being undertaken in the Manchester Interdisciplinary Biocentre (http://www.mib.ac.uk).

If you are interested in appling for this project, please contact the named supervisor.

Magnetisation dynamics in energy assisted magnetic data storage materials

Supervisor: Prof Tom Thomson

FMR Spectra

Magnetisation dynamics is a very broad research field and our interest is in the dynamics of thin film materials and particularly nanomagnetic systems. This project is focussed on developing experimental understanding of the physical properties which control the dynamic response of materials. The dynamic behavior of magnetic materials is critical in any data storage application as these systems are increasingly required to supply and record information at GHz rates. Very recently a new class of energy assisted recording technology where microwave power is provided in additional to a short magnetic field pulse has been proposed. Is this the principal behind microwave assisted magnetic recording (MAMR). Here the excitation of magnetization dynamics where a precession of the moment is established allows the magnetization to switch at lower applied fields than would otherwise be the case allowing higher anisotropy materials to be used and so postponing the point at which superparamagnetism degrades data retention.

In this project involves using ferromagnetic resonance (FMR) to characterize the damping parameter α in data storage materials. The work will involve creating devices and techniques for FMR experiments on novel perpendicular exchange spring materials. As an example, figure 1 shows some earlier work on longitudinal data storage media where the FMR signal was measured for a series of media with different boron concentration. These measurements not only allow the anisotropy field to be probed but also provided new information on the damping processes in these materials.

The figure illustrates FMR spectra measured in the range 75 91 GHz for a series of longitudinal magnetic recording media as a function of boron content.

If you are interested in appling for this project, please contact the named supervisor.

Optical interactions in magnetic nanostructures

Supervisors: Prof Tom Thomson and Dr Paul Nutter

MOKE system at Manchester

The optical response of magnetic materials through the Kerr and Faraday effect have long been used to characterize magnetic thin films. Typically the Kerr effect is used whereby upon reflection the plane of polarization of a linearly polarized incident beam is rotated and reflection from an infinite (compared with the wavelength of the incident laser) thin film surface is well known. However, recently a number of intriguing effects have been discovered when instead of a planar surface, light is incident on a nanoscale patterned surface such as that found in bit patterned media (BPM). Here, the magnetic structures are much smaller than the wavelength of the light e.g. the nanostructures are below 50 nm in all 3 dimensions whereas lasers with λ = 633 nm are typically used in experiments. The observed effects include changes in both the sign and magnitude of the Kerr rotation. This suggests some interesting questions which require further investigation in order to understand the physical origin of the observations and the potential uses. As a minimum understanding the interaction of light with patterned magnetic surfaces is a key challenge if optical techniques are to be used to characterize BPM.

This project involves enhanced optical instrumentation designed to give the capability necessary to study the small magnetic structures at different wavelengths and applied magnetic fields. In will also involve creating patterned magnetic structures with well defined dimensions and magnetic properties using the methods developed by the NEST group.

The image shows the optical system for small spot ( λ < 5 μm) magneto-optic Kerr effect measurements.

If you are interested in appling for this project, please contact the named supervisor.

Numerical simulation of nano-carbon fluid-phase sorting

Supervisors: Dr Milan Mihajlovic, Dr Aravind Vijayaraghavan, and Prof. Matthias Heil (Mathematics)

One of the critical aspects of Graphene and Carbon Nanotube (CNT) research is the development of stable suspensions of these nano-carbons in various aqueous and organic solvents. Such suspensions have been obtained experimentally and used as a starting point for fluid-phase sorting of CNTs by chirality, diameter and length, and, in the case of graphene, by the size and the number of layers. We need to say why is this relevant in nano-research. A number of research groups are actively pursuing this problem experimentally. By contrast, the results from numerical simulations are far less common in the literature. Creating a viable mathematical model for this complex physical system and simulating it on a computer would enable better understanding and prediction of the regimes for efficient dispersion and separation that would otherwise be sought through expensive and time consuming experimentation by trial and error.

The aim of this project is to develop and implement a computational model for nano-carbon fluid-phase sorting. In the first approximation nano-carbon particles will be treated as continuous rigid bodies and the resulting fluid-solid interaction multi-physics system will be discretised using the finite element method. The implementation of the computational model will be done within OOMPHLIB (the Object Oriented Multiphysics Library – see [1]). The library provides a framework for monolithic finite element discretisation of multiphysics problems. The library currently supports the discretisation of problems in fluid and structural mechanics using variery of uniform and adaptively refined grids, algorithms for adaptive timestepping and a library of multigrid-based preconditioned iterative solvers for linear algebraic systems. Upon successful implementation of the model, the student will perform extensive parameter study, comparing the numerical with experimental results from the literature and trying to identify the regimes of efficient separation which will drive and direct further experimental work. Do we want any refinement of a simple solid model for carbons/inclusion of thermal effects?

Desirable skills: strong mathematics and physics/material background, C/C++ programming.

References: 1. OOMPHLIB - http://www.maths.manchester.ac.uk/~mheil/oomph-lib/index.html