Colóquios do Departamento

Colóquios Realizados em 2014/2015

Quarta-feira dia 1 de Julho, às 11h00m

"Perpendicular magnetic anisotropy: from ultralow power spintronics to cancer therapy"

Orador: Professor Russell Cowburn - IEEE distinguished Lecturer 2015, Univ. Cambridge, Reino Unido

Local: Anfiteatro VA3 (IST, Pavilhão de Civil)

Most thin magnetic films have their magnetization lying in the plane of the film because of shape anisotropy. In recent years there has been a resurgence of interest in thin magnetic films which exhibit a magnetization easy axis along the surface normal due to so-called Perpendicular Magnetic Anisotropy (PMA). PMA has its origins in the symmetry breaking which occurs at surfaces and interfaces and can be strong enough to dominate the magnetic properties of some material systems. In this talk I explain the physics of such materials and show how the magnetic properties associated with PMA are often very well suited to applications. I show three different examples of real and potential applications of PMA materials: ultralow power STT-MRAM memory devices for green computing, 3-dimensional magnetic logic structures and a novel cancer therapy.

Russell Cowburn has research interests in nanotechnology and its application to magnetism, electronics and optics. Before returning to Cambridge in 2010 he held positions at the CNRS Paris, University of Durham and Imperial College London. He is the founder of two start-up companies and the inventor of the anti-counterfeiting technology ‘Laser Surface Authentication’. He has had over 60 patents granted and is a frequent invited speaker at international conferences. He is the winner of the GSK Westminster Medal and Prize, the Degussa Science to Business Award, the Hermes International Technology Award and the Institute of Physics Paterson Medal and Prize. He is a Fellow of the Royal Society.

27 de Maio, às 16h30m

"Topological Matter and Why You Should be Interested"

Orador: Steve Simon, Universidade de Oxford

Local: Anfiteatro PA1 (IST, Pavilhão de Matemática, piso -1)

In two dimensional topological phases of matter, processes depend on gross topology rather than detailed geometry. Thinking in 2+1 dimensions, particle world lines can be interpreted as knots or links, and the amplitude for certain processes becomes a topological invariant of that link. While sounding rather exotic, we believe that such phases of matter not only exist, but have actually been observed in quantum Hall experiments, and could provide a uniquely practical route to building a quantum computer. Possibilities have also been proposed for creating similar physics in systems ranging from superfluid helium to strontium ruthenate to semiconductor-superconductor junctions to quantum wires to spin systems to cold atoms.

20 de Maio, às 16h30m

"Light Forces"

Orador: Heinrich Hoerber, Univ. Bristol, Reino Unido

Local: Anfiteatro PA1 (IST, Pavilhão de Matemática, piso -1)

The Year of Light 2015 emphasises the significance of the natural phenomenon of light for us. Our sense of seeing establishes the main channel that provides us with information about the world we are living in and it is the only channel that provides information about distant objects like planets and stars.

In my talk, I would like to focus on a very special effect of light when it interacts with matter: it can exert forces. The first one that we know of, who recognised this effect, was Johann Kepler when he thought about why comet tails always point away from the sun. The linear momentum of light involved is meanwhile used in many applications from cooling atoms to optical tweezers. For me the most fascinating application in future might be to accelerate space ships.

Beside the linear momentum light also has an angular momentum related to the spin of a photon or to an additional orbital momentum, which some modes of laser light can exhibit. As we know from fundamental Mechanics, an angular momentum can be converted into a linear momentum when a force acts in an unsymmetric way on a rotation. For instance, if the wheel of a bicycle turns in air and then touches ground, a part of the angular momentum is transferred into a linear motion by a counteracting force to the friction force on the axel. A force generated in a comparable way from the angular momentum of light, obviously, will be very small and it is rather challenging to measure it. I will describe such a measurement that complements measurements by Raman and Beth in the 1930ties of the torque generated by light hoping to add to the understanding of the phenomenon of light.

29 de Abril de 2015, às 16h30

"Tokamak fusion plasmas and modelling infrastructures"

Orador: Rui Coelho, Instituto de Plasmas e Fusão Nuclear, IST

Local: Anfiteatro PA1 (IST, Pavilhão de Matemática, piso -1)

The quest for competitive advantage in modern societies boosts research. Fusion research is a vibrant field with an ambitious goal of mastering controlled fusion burning plasmas in devices on Earth and producing clean electricity with virtually unlimited resources. Extensive research on magnetic plasma confinement devices known as Tokamaks have revealed the essential role that modelling plays in data interpretation of present experiments and building up predictive capability for future devices. In this talk, the spur behind Tokamak research and physics is reviewed and focused on computational infrastructures implementations dedicated to Tokamak modelling.

22 de Abril de 2015, às 16h30

"HiSPARC: Undergraduate research, outreach and development"

Orador: Filipe Freire, Instituut-Lorentz for Theoretical Physics, Univ. Leiden

Local: Anfiteatro PA1 (IST, Pavilhão de Matemática, piso -1)
HiSPARC is a physics outreach cosmic rays experiment initiated in the Netherlands that brings together, research, education and networking. Using low cost scintillator plates as cosmic ray detectors placed in universities, secondary schools and public institutions, this experiment brings secondary school students in contact with real research data involving the mysterious high energy cosmic rays. In addition students in this project have an opportunity to have first hand contact with the technology, data analysis and networking required to run physics experiments. A summary of the present status and aims of this project is presented.