Materials that respond to an electric or magnetic signal are crucial to many modern technologies, including data storage, ultrasound sensors and low temperature cooling. They also exhibit fascinating fundamental phenomena as seen by the awarding of the 2016 Nobel Prize for theoretical understanding of topological phases. Recently new classes of materials that contain both inorganic and organic building blocks have attracted attention for their ability to exhibit such magnetic and electronic functionalities. These include coordination frameworks where transition metal or lanthanide cations are connected together by organic ligands to make extended structures. The tremendous choice of building blocks for such materials provide enormous flexibility to tailor their properties for particular applications, while the unique structures they adopt allow properties to be varied in ways not possible in conventional ferroic materials. This includes well-isolated low dimensional structures well suited to low dimensional magnetism. The origins of these properties in the atomic level structure and dynamics of frameworks is, however, currently obscured. Our group’s focus is to develop a fundamental understanding of the microscopic origins of these properties in frameworks and use this to develop design rules for improved properties. Recent examples of this will be discussed including:
1) Probing the magnetic and ferroelectric ordering of transition metal formate frameworks that exhibit both ferroelectric and magnetic order to uncover unique trends in their magnetic structure and unusual origins for relaxor ferroelectric type behaviour.
2) Lanthanide frameworks with potential for low temperature magnetic based cooling in the low applied fields practical for a functional device. These materials often have 1D ferromagnetic coupling in their paramagnetic phase and are also hosts to frustrated magnetic interactions. These combine to support the emergence of unique states, including a terbium formate framework with partial 1D long-range magnetic order.
Biography: Dr Paul Saines holds a BSc. (2004) from the University of Sydney and completed a PhD (2008) under the supervision of Prof. Brendan Kennedy, working on solid-state oxide chemistry at the same institution. In 2009 he started as a postdoctoral researcher working on magnetic metal-organic frameworks under the supervision of Prof. Anthony Cheetham at the University of Cambridge. From 2013 he was a Glasstone fellow at the University of Oxford hosted by the group of Prof. Andrew Goodwin, where he focused on ferroic and magnetocaloric frameworks. He was then appointed as a Lecturer at the School of Physical Sciences at the University of Kent in 2015. The research in his group focuses on the synthesis and characterisation, including neutron scattering, of dense metal-organic frameworks with interests in multiferroics, low dimensional and frustrated magnetism.