196th Special MMU seminar
What can be done with Manganese?
Prof. J. M. D. Coey
School of Physics and CRANN, Trinity College, Dublin 2, Ireland.
Date: June 24(Tue), 2014
Time: 10:30 - 11:45
Place: 8th floor medium seminar room (Room 812), Sengen
Manganese is one of the most distinctive magnetic elements in the periodic
table. The d band is more than half full, yet manganese is not
ferromagnetic. ƒ¿-Mn has the largest and most complex unit cell of any
element, containing 48 atoms in four inequivalent sites with moments
ranging from 0.5 ƒÊB to 2.8 ƒÊB that order in a complex triangular
antiferromagnetic structure below 90 K. Nevertheless, Mn-rich alloys exist
with ferrimagnetic structures and high Curie temperatures, which are of
potential interest for various applications. The tetragonal D022 -
structure Mn-rich Mn-Ga and Mn-Ge alloys have magnetocrystalline anisotropy
of up to K =2.5 MJm-3, and a magnetization that depends on the site
occupancy. Mn3Ga has an unusual ferrimagnetic structure with a soft
in-plane component. Results on both bulk and highly textured thin films are
presented. The first experimental example of a zero-moment half metal,
cubic Mn2Ru0.5Ga in thin film form will also be introduced.