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Physics Colloquium - Emeritus Professor Joe Trodahl

Monday, 7 August 2017

Physics Department

Emeritus Professor Joe Trodahl

School of Chemical and Physical Sciences

Victoria University of Wellington

"Rare-Earth Nitrides; Semiconductors, Spin/Orbit Ferromagnetism, Spintronics..."

Spintronics, controlling the flow of electronic spin in addition to the charge, promises speed and power-demand advantages. But there are as yet few spintronic devices on the market, in part due to a lack of intrinsic ferromagnetic semiconductors that would permit full exploitation of the coupled spin/charge technology. To date the only series of such materials are the mononitrides of the lanthanides, the 14 rare-earth elements. Many of the LN (L a lanthanide element) are semiconductors, with strongly contrasting magnetic properties from the coupled spin and orbital moments residing in the lanthanide 4f shells.1 We started investigating epitaxial and polycrystalline film growth and electronic-magnetic properties of these compounds ten years ago. In the past few years we began work on LN/L’N heterostructures. Furthermore we have investigated integration with both the optical III-V semiconductors and superconductors of interest for their potential in central processors. Along the way there have been many surprises, most recently that one of the series, near-zero magnetisation ferromagnetic SmN, is superconducting below 4 K.2
My talk will cover the lot, the growth conditions and crystal structure, control of their carrier concentration, investigations of their coupled magnetic/electronic properties, tunneling in device-like structures and the observation of the remarkable superconductivity in doped SmN.

1. F. Natali et al, Prog, Materials Science 58, 1316 (2013)
2. E.-M. Anton et al. Phys. Rev. B 94, 024106 (2016)

WHEN: Monday 7 August 2017
WHERE: Room 314, Science 3 Building
TIME: 3.00 pm–4.00 pm

All interested are welcome to attend

Light refreshments to follow in Common Room