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Welcome Statement
The physical reality of our world is often complicated and difficult to unveil. Fortunately now it can be efficiently simulated in a computer. In fact in many situations, when experiments are too complicated, too expensive or too difficult to interpret, or when there are no experiments at all, it is useful to perform computational experiments. In these one solves with a computer the fundamental laws governing the physical phenomena. Such an approach has become a successful strategy in materials science and device designing and it is now invading other scientific areas such as biology and in a future medicine. However "teaching" to a computer how to solve a problem is complicated in itself. The research program of the Computational Spintronics Group at Trinity College Dublin aims at developing a series of sophisticated methods for simulating small-scale devices, in particular including magnetic elements. These allow us to predict their properties ahead of experiments and to tackle challenging problems with a potential for generating novel revolutionary devices. Such devices are then pursued experimentally by our colleagues at the Center for Research on Adaptive Nanostructures and Nanodevices (CRANN).
Stefano Sanvito
Latest News and Research Highlights
16 September 2009
The Electrostatic Spin-Crossover Effect
The magnetic configuration of a nanostructure can be altered by an external magnetic field, by spin-transfer torque or via its magneto-elastic response. Now there is an alternative route, namely the possibility of switching the sign of the exchange coupling between two magnetic centers by mean of an electric potential. This general effect, that we name "electrostatic spin crossover", occurs in insulating molecules with super-exchange magnetic interaction and inversion symmetry breaking. Taking as an example a family of di-cobaltocene-based molecules we have demonstrated that the critical fields for switching, calculated from first principles, are of the order of one V/nm and can be achieved in two-terminal devices. More crucially such critical fields can be engineered with an appropriate choice of substituents to add to the basic di-cobaltocene unit. This suggests that an easy chemical strategy for the synthesis of suitable molecules is possible.
24 August 2009
A spin of their own
Although it is tempting to compare organic semiconductors with their inorganic counterparts, the spin-injection and spin-transport properties are fundamentally different. The challenges in understanding and improving such properties make organic spintronics an exciting field in its own right.
5 May 2009
Magnetic state electrical readout of Mn12 molecules
We demonstrate that the different magnetic states of a Mn12 molecule can be distinguished in a two-probe transport experiment from a complete knowledge of the current-voltage curve. Our results, obtained with state-of-the-art non-equilibrium transport methods combined with density functional theory, demonstrate that spin configuration-specific negative differential resistances (NDRs) appear in the I-V curves. These originate from the interplay between electron localization and the re-hybridization of the molecular levels in an external electric field and allow the detection of the molecule's spin-state.
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