page_title: Single-molecule magnet
section_title: Applications
hierarchical_section_title: Single-molecule magnet / Applications
caption_attribution_description: A hard disk head and platter
context_page_description: A single-molecule magnet is a metal-organic compound that has superparamagnetic behavior below a certain blocking temperature at the molecular scale. In this temperature range, a SMM exhibits magnetic hysteresis of purely molecular origin. In contrast to conventional bulk magnets and molecule-based magnets, collective long-range magnetic ordering of magnetic moments is not necessary.
  Although the term "single-molecule magnet" was first employed in 1996, the first single-molecule magnet, [Mn₁₂O₁₂(OAc)₁₆(H₂O)₄] was reported in 1991. This manganese oxide compound features a central Mn(IV)₄O₄ cube surrounded by a ring of 8 Mn(III) units connected through bridging oxo ligands, and displays slow magnetic relaxation behavior up to temperatures of ca. 4 K.
  Efforts in this field primarily focus on raising the operating temperatures of single-molecule magnets to liquid nitrogen temperature or room temperature in order to enable applications in magnetic memory. Recent acceleration in this field of research has resulted in significant enhancements of single-molecule magnet operating temperatures to above 60 K.
context_section_description: There are many discovered types and potential uses. Single-molecule magnets represent a molecular approach to nanomagnets (nanoscale magnetic particles).
  Due to the typically large, bi-stable spin anisotropy, single-molecule magnets promise the realization of perhaps the smallest practical unit for magnetic memory, and thus are possible building blocks for a quantum computer. Consequently, many groups have devoted great efforts into synthesis of additional single-molecule magnets.
  In addition, single-molecule magnets have provided physicists with useful test-beds for the study of quantum mechanics. Macroscopic quantum tunneling of the magnetization was first observed in Mn₁₂O₁₂, characterized by evenly spaced steps in the hysteresis curve. The periodic quenching of this tunneling rate in the compound Fe₈ has been observed and explained with geometric phases.
caption: One possible use of SMMs is superior magnetic thin films to coat hard disks.
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