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Transition Metal Perovskites

< New magnetic materials based on carbon | ResearchLines | Strongly correlated electron systems: fullerides >

We have been working on two main families of perovskites in the past years: cuprates, which host the high Tc superconductors, and manganites, which host a fully spin polarized metal phase, based on the Double Exchange mechanism. In both cases a metal phase with exotic properties can be obtained by compositional variations of magnetic transition metal oxides, sharing the same type of crystal structure. The onset of superconductivity and the underlying insulator-metal transition is still the focus of our attention in the cuprates. The origin of the half metallic behaviour of manganites stimulated our interest towards other transition metal oxides, notably magnetite, and the yet unveiled secrets of the Verwey transition. The applicative aspects of half metals triggered our collaborations with film growers, towards the characterization of subtle interfacial properties of artificial multilayered structures.

The plot on the left shows the phase diagram for YBa2Cu3O6+x: like in all high Tc cuprate materials substitution leads to charge doping of the CuO2 layers, which in turns disrupts the underlying antiferromagnetic order - signalled here by the blue points of the Neel temperature TN - and gives rise to superconductivity - halmarked by its Tc (red points, notice the logarithmic scale). See also the highlight

The most intriguing aspect that we have been recently exploring on cuprates regards the effect of local structure and disorder on the onset of superconductivity. We have started to find systematic evidence that charge doping by itself is by no means the most important parameter around the onset region for superconductivity. Investigation is in progress on the system Y1-yCayBa2Cu3O6+x to clarify this important aspect.

Cuprates Manganites
Samuele Sanna Giuseppe Allodi
Francesco Coneri Marco Bimbi
Roberto De Renzi Andrey Sidorenko
Roberto De Renzi
MIUR FIRB 2002-2007 MIUR FIRB 2002-2007
MIUR PRIN 2006-2008 FPVI STREP-OFSPIN 2007-2009
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Page last modified on February 01, 2007, at 07:20 PM