Professor Gregg obtained a D Phil in nuclear magnetism of Van Vleck systems under the guidance of B. Bleaney and F. N. H. Robinson and made the first observation of Enhanced Nuclear Acoustic Resonance. Later he worked as a Collaborateur Etranger in Commissariat a l’Energie Atomique Francais, preparing and studying ordered nuclear states in the research team of A. Abragam. As a Royal Society Research Fellow he made the first microwave acoustic interferometry study of the dynamics of time-reversed metastable antiferromagnetic states. In Spintronics, he made the first observation of Giant Magnetoresistance (GMR) of a mechanical alloy, the first observation of Giant Thermal Magnetoresistance and he first proposed and confirmed experimentally a new spin-dependent model for the electrical resistance of a ferromagnetic domain wall. He has held Visiting Professorships in Strasbourg, Paris and Dublin. He holds 19 patents and he has acted on four occasions as an expert witness in the British courts in both Spintronics and Nuclear Quadrupole Resonance and in the European Patent Court as an expert on analogue electronic instrumentation. He is the Academic Founder of an Oxford University spinout company.
Professor Gregg teaches Condensed Matter Physics, Quantum Mechanics, Atomic Physics, Photonics and Laser Physics, Mathematics for Physicists, Thermodynamics, Statistical Mechanics, Kinetic Theory, Geometrical and Wave Optics, Electromagnetism, Electronics and Circuit Theory, Electrical Power and Machines, Radiofrequency and Microwave Techniques, Communications and Instrumentation.
Spintronics, phonon coupling in Magnon-Spintronic systems, microwave design, radiofrequency sensing devices, thin film fabrication, NMR and NQR instrumentation, novel control of electrical machines, development of innovative wind-turbine technology; application of novel control techniques to separation devices for medical engineering; commercial applications of compact microwave sensors.