Magnetic properties superconductors

Keywords M(dmit)2, Metal bis(dithiolene), Metallocenium, Radical cations, Spin crossover, Magnetic properties, Superconductor... 

Dimensions. Most coUoids have aU three dimensions within the size range - 100 nm to 5 nm. If only two dimensions (fibriUar geometry) or one dimension (laminar geometry) exist in this range, unique properties of the high surface area portion of the material may stiU be observed and even dominate the overaU character of a system (21). The non-Newtonian rheological behavior of fibriUar and laminar clay suspensions, the reactivity of catalysts, and the critical magnetic properties of multifilamentary superconductors are examples of the numerous systems that are ultimately controUed by such coUoidal materials. 

As will be discussed later (Section 1.5), molecules containing no metallic elements are able to combine and form materials exhibiting metallic character, e.g., HMTSF-TCNQ, TTF-TCNQ, etc., or even lose any electrical resistance below a given temperature and thus become superconductors, e.g., (TMTSF)2C104. Metal-free molecules can also, in the solid state, show magnetic order, such as / -NPNN and /7-NC-C6F4-CNSSN, where in the absence of -electrons the magnetic properties are related to unpaired -electrons. 

In passing, it should be noted that Michel and Raveau had carried out electrical measurements on several alkaline-earth substituted La2Cu04 compounds and presented (140) their experimental results in a comprehensive review during 1984. Their work, however, was primarily structural with a focus on electrical and magnetic properties above 50 K for this reason they missed observing the superconducting transition at 30 K. It is this author s belief that these Cu-O phases should be called the "Raveau-Michel" phases in much the same way as the molybdenum sulfide superconductors are called the "Chevrel" phases. 

J.M. Williams and K. Carneiro, "Organic Superconductors Synthesis, Structure, Conductivity, and Magnetic Properties", pp. 249-296, in "Advances in Inorganic Chemistry Radio-chemisiry , Vol 29, Academic Press, Inc. (1985). 

Static Magnetic Properties of High-Temperature Superconductors... 

A.P. Malozemoff, "Macroscopic Magnetic Properties of High Temperature Superconductors", in Physical Properties of High Temperature Superconductors /, ed. by D. M. Ginsberg, World Scientific, Singapore, Ch. 3, and references therein (1989). 

Most of the important magnetic ceramics are of the ferrimagnetic class. However, some ceramics do exhibit other types of magnetic behavior. These ceramic materials will be described first, followed by a more thorough description of an important class of ferrimagnetic ceramics called ferrites. Finally, a topic related to the magnetic properties of ceramic superconductors will be introduced. 

The remaining chapters each deal with a property or a special class of solid. Chapter 4 covers low-dimensional solids, the properties of which are not isotropic. Chapter 5 deals with zeolites, an interesting class of compounds used extensively in industry (as catalysts, for example), the properties of which strongly reflect their stracture. Chapter 6 deals with optical properties and Chapter 7 with magnetic properties of solids. Finally, Chapter 8 explores the exciting field of superconductors, particularly the relatively recently discovered high temperature superconductors. 

---