Interfacial magnetism in topological insulator heterostructures

Project Description:

Finding materials with zero electrical resistance, i.e., 'perfect' conductors, has become a holy grail of condensed matter physics. Topological insulators can host dissipationless electrical transport channels without the need for low temperatures, high pressures, or high magnetic fields. This phenomenon is called the quantum anomalous Hall effect and requires that magnetic order is introduced to the nonmagnetic topological insulator, which is a huge technological challenge due to defects associated with the commonly employed doping method. In contrast, by combining a topological insulator and an antiferromagnet in an intrinsic system, no intermixing will take place and the magnetic order is induced due to proximity coupling. Theory predicts that this approach leads to higher robustness of the magnetic ordering and the homogeneity of the underlying polarisation raise the expectation that the quantum anomalous Hall effect can be observed at higher temperatures.

The project aims at achieving this goal by combining a topological insulator and an antiferromagnet by atomically controlled molecular beam epitaxy growth. The project will make use of the unique capabilities offered by Diamond, ISIS and Oxford Physics, by carrying out a complementary multi-method study of the pristine electronic and magnetic properties of ultrathin films. Synchrotron-based techniques such as XMCD/XMLD and photoemission spectroscopy, in concert with neutron-based reflectivity and magnetotransport measurements will allow a unique insight into the inner workings of these exciting quantum materials.

Our coherent, multi-method approach will provide a superb training and research environment for the student.  The student will be mainly based on the Harwell Campus. Combining topological insulators and antiferromagnets has the potential to be the platform for the next generation of energy-efficient electronic devices and will have applications in metrology and potentially topological quantum computing.

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Kindly note, each project is not guaranteed to go ahead at this stage until there is a signed agreement in place between Diamond and the University.

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