Tunneling in magnetic molecules
Cambridge University Press, 1998
Online
unknown
Zugriff:
Magnetic molecules represent another interesting area for MQT studies. In this chapter we will describe experiments on spin tunneling in macroscopic crystals of Mn 12 Ac molecules. A Mn 12 Ac molecule has spin 10 and is equivalent to a very small single-domain magnetic particle. A crystal consists of a macroscopic number of molecules arranged in a tetragonal lattice. Spins of the molecules interact weakly with each other and are subject to a very strong uniaxial anisotropy. A Mn 12 Ac crystal is, therefore, equivalent to a large system of identical uniformly oriented magnetic particles, which has been wanted so much by experimentalists. Experiments on Mn 12 Ac [16] are the first experiments on spin tunneling which have been understood quantitatively without any free parameters. Whether the moment of the molecule, 20μ B , is macroscopic enough to allow one to talk about MQT is left to the judgement of the reader. The Mn-12 acetate complex The chemical formula of the manganese acetate complex discussed below is [Mn 12 O 12 (CH 3 COO) 16 (H 2 O) 4 ]·2CH 3 COOH·4H 2 O. We will denote it by Mn 12 Ac. This compound was first synthesized by Liz and characterized by Xray diffraction methods [128]. It forms a molecular crystal of tetragonal symmetry with the lattice parameters a = 1.732 nm and b = 1.239 nm. The unit cell contains two Mn 12 O 12 molecules surrounded by four water molecules and two acetic acid molecules. The structure of the Mn 12 O 12 molecule is shown in Fig. 7.1. The molecule possesses S 4 symmetry.
Titel: |
Tunneling in magnetic molecules
|
---|---|
Autor/in / Beteiligte Person: | Tejada, Javier ; Chudnovsky, Eugene M. |
Link: | |
Veröffentlichung: | Cambridge University Press, 1998 |
Medientyp: | unknown |
DOI: | 10.1017/cbo9780511524219.008 |
Schlagwort: |
|
Sonstiges: |
|