InternalSummerPlacements2016
Internal Summer Placements 2016
Projects for SUMMER 2016
Title: Defects in Spin Ice
Supervisor: Professor Jon Goff
Duration: 8 weeks
The proposal for the observation of magnetic monopoles in spin ice [1] has enjoyed much success in the intermediate temperature regime [2,3]. However, low-temperature measurements now point to the importance of defects in monopole dynamics, in providing extrinsic resistance for monopole currents [4]. This project is to study the defect structures of spin ice materials using x-ray diffraction. The work will include the measurements of single crystals using the x-ray equipment at Royal Holloway, structural refinement of the Bragg reflections, and computer simulations of the diffuse scattering.
[1] C. Castelnovo et al., Nature 451, 42 (2008) [2] D.J.P. Morris et al., Science 326, 411 (2009) [3] T. Fennel et al., Science 326, 415 (2009) [4] H.M. Revell et al., Nature Physics 9, 34 (2013
Title: Studying Top quark events at ATLAS
Supervisor: Dr Veronique Boisvert
Duration: 8 weeks
This project will focus on using simulated events from ATLAS and using C++ code to analyse those events. The student will learn more about the particle physics done at the LHC and focus on learning about the top quark, in terms of its production, its decay and interesting signatures and its connection with the Higgs boson. Although an interest in programming is necessary as this project is purely computing based, prior knowledge of C++ is not required.
Title:Development of advanced instrumentation for charged particle beam using Cherenkov Diffraction Radiation
Supervisor: Dr Pavel Karataev
Duration: 8 weeks
Title: Novel electronic states including unconventional superconductivity at the border of magnetism
Supervisor: Dr Philipp Niklowitz
Duration: 8 weeks
This research activity in which this project will be embedded has the aim to explore novel states of electronic matter including unconventional superconductivity. We focus in particular on electronic systems in the vicinity of magnetic order. Some states like conventional metallic states or conventional superconductivity are already well understood. However, magnetic interactions between conduction electrons, which are enhanced near magnetic quantum phase transitions can lead to more exotic states of matter.
Experimentally, magnetic quantum phase transitions are reached by cooling a magnetically ordered material to low temperatures and tune the system at low temperatures. We use high-pressure techniques for tuning. The project student will become familiar with high-pressure and low-temperature techniques. The student will have the opportunity to contribute to the exploration of pressure-temperature phase diagrams of promising candidate materials, which might include recently discovered Fe-based superconductors.
Title: Projects within the Low Temperature Lab
Supervisor: see individual projects
Duration: 8 weeks
Project 1 (John Saunders/Jan Nyeki)
Interactions, transport and superfluidity in a 2D Fermi gas
3He bound in surface states on a superfluid 4He film adsorbed in turn on the surface of graphite is an ideal model system to investigate strong correlations in a 2D Fermi gas of tuneable density, with tuneable interactions. Our objective is to find superfluidity in a strictly 2D monolayer of fermions; here we have a model system to potentially realise this quantum state. Such an observation would be of broad significance in condensed matter physics. Our system is cooled to 200 microK and probed by highly sensitive SQUID NMR techniques developed in our laboratory. Studies of the thermodynamic properties of this system are underway using exfoliated graphite substrates on a nuclear adiabatic demagnetization refrigerator (ND1). A current challenge is to develop and exploit new high quality substrates (CVD graphene is one candidate) to eliminate disorder that may suppress superfluidity, and to open up the possibility of spin transport measurements for the first time. The intern would join and participate in this project learning about: ultralow temperature technology; NMR; SQUID technology; fundamental physics of 2D fermi systems.
Project 2 (John Saunders/Andrew Casey)
Order parameter sculpture of confined topological superfluid 3He and its surface excitations
Superfluid 3He is of central importance in the rapidly developing field of topological quantum matter. There are no clearly established topological superconductors, while 3He is a p-wave “neutral” superconductor with two distinct phases, one (ABM) chiral and the other (BW) time reversal invariant. At Royal Holloway we have pioneered the study of this topological superfluid under precisely engineered nanoscale confinement. The goals are to study Majorana surface excitations, emerging as a consequence of bulk-surface correspondence and to use confinement to stabilize new order parameters, with different broken symmetries from those stable in bulk. This requires the development of new experimental techniques for investigating the nanophysics of superfluid 3He, and its surfaces, where confinement is the new control parameter. Ongoing studies concern the influence of progressively strong confinement, on length scales of order the coherence length, on slab-like cavities, using SQUID NMR developed in our laboratory and a nuclear adiabatic demagnetization refrigerator (ND2). Side-by-side we are working on methods to investigate the transport properties of the confined superfluid: the ultimate goal is to fingerprint Majorana fermions. The intern would join and participate in this project learning about: ultralow temperature technology; NMR; SQUID technology; fabrication of nanofluidic geometries; help develop new techniques; fundamental physics of topological superfluids.
Project 3 (Andrew Casey/John Saunders)
Brute force cooling on NEMS towards the quantum limit
There is a growing interest in nano-electromechanical resonators (NEMs) at ultralow temperatures. At Royal Holloway we have been working on SQUID detection of high Q nano-mechanical resonators at milliKelvin temperatures. This modular design of our set-up allows us to optimise NEMS (typical Q is 106 or more), and control magnetic field on NEMS for magneto-motive readout over a wide range. The low temperature platform is a cryogen-free dilution refrigerator, where we have previously developed the first cryogen-free nuclear adiabatic demagnetization refrigerator [ND4]. We have observed: the thermal motion of the undriven NEMS down to 20 mK; characterised the back action; observed single mode cooling from the bath temperature by up to a factor of 5; and by changing the SQUID bias we can observe self-sustained oscillations. We are working to extend this work to higher frequencies and temperatures below 6mK: to approach quantum limit by brute force, and to use NEMs to probe liquid helium.
Title: Condensed Matter Physics
Supervisor: Dr James Nicholls
Duration: 8 weeks
As part of a collaboration (samples and theory from Cambridge & UCL) we wish to cool the electrons in semiconductor devices down to less than 1 mK. This has never been achieved before and in low-dimensional systems such as 1D wires and 0D quantum dots it is predicted that electrons will order into new quantum states. In this project there will be a variety of activities that will contribute to the setting up of preliminary measurements on new equipment: testing semiconductor devices at 4.2 K, making and testing filters for low noise measurements, writing software to control equipment or analyse data, modelling, etc. There will be opportunities to develop new skills and to work in a team of researchers (post docs, academics, technicians).
Title: Condensed Matter Physics
Supervisor: Vladimir Antonov
Duration: 8 weeks
Experimental Nanotechnology- details to be confirmed
Title: Study of ttH events at ILC
Supervisors: Dr. M. Faucci Giannelli Duration: 8 weeks
The ILC is the next generation electron-positron collider and is currently in the final stage of design. One of the main criteria for deciding the final detector design is the performances of several physics benchmarks; ttH is one of them. The student will learn about particle physics and in particular about Higgs and top physics at ILC. The student will learn to write code in C++ which will be used to select ttH events using the ILD detector official simulation. This project is purely software based and, although C++ knowledge is not required, it is a desirable skill for this project.
Title: tba
Supervisors: Gary Boorman, Stephen Gibson
Normally a project involving Labview
Title: Outreach and Teaching Equipment Upgrade
Supervisors: Stephen Gibson and Ian Murray
Duration: 8 Weeks
The department runs a wide variety of public outreach activities and events. The range of demonstrations and equipment for these is constantly being upgraded and expanded. This project will focus on designing some new demonstrations as well as upgrading existing ones. Specifically, this summer we are hoping to design a new water based invisibility cloak and a circularly polarized RF gun. Upgrades are planned for our Dark Matter machine, Ripple Tank and Chladni Plate demonstrations. In addition, the project would involve improving the documentation for some current demos. The work for this project would involve researching and designing these new demonstrations with guidance, as well as working to build and test them.
Title: Spin entanglement as a key process for condensed matter physics
Supervisors: Anna Posazhennikova
Theoretical condensed matter physics