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Robinson Group

 

This project with Dr Atature (Cavendish) combines two radically different materials and fields of research, namely oxide interfaces and diamond nanocrystal magnetic resonance imaging (diamond nano-MRI) in order to reveal the exact nature of low-dimensional magnetic phenomena with nanometre spatial resolution and single-spin level sensitivity. Coherent control protocols developed for isolated and confined spins in diamond are used to detect faint magnetic fields due to spin ordering near, or at ,the oxide interfaces. This level of investigation surpasses all previous measurements to-date in terms of spatial resolution or degree of sensitivity. The aim is to exploit this sensitivity to answer a wide range of open questions in novel magnetism over a wide range of temperatures.

 

Interface magnetism is a rapidly developing area. The most topical example in oxides is found at the LaAlO3/SrTiO3 (LAO/STO) interface (the system we are mainly working with). Here interface charge transfer results in a two‐dimensional electron gas (2-DEG) in the STO side of the interface. Nevertheless,  the origin of the different spin symmetries at exist at the interface remains controversial due to the competing influence of oxygen defects and the unexplained role of interfacial dopants in suppressing carrier density. This means that the exact localisation of symmetry states to the interface remains to be one of the most debated problems in the field.

 

The aim of this project is to resolve the long-standing debate of where the magnetism in LAO/STO and LMO/SMO originates by mapping the spatial extent of the magnetism around the interface with a nanometer-scale resolution using diamond nano-MRI. Furthermore, we aim to demonstrate that diamond-based Nano-MRI is versatile tool for probing spin physics at interfaces.

 

This research programme is a collaboration with Dr Chris Bell at SLAC, Stanford, USA.