title: Tuning magnetic properties of Mn(4) cluster with gold coating.
abstract: The magnetic properties of transition metal clusters are a unique function of their size and differ from their bulk behavior due to quantum confinement. Here we show that surface modification provides another channel to tune their magnetic properties. This is demonstrated by taking Mn(4) as an example. Although Mn(4) carries a giant magnetic moment of 20 micro(B), the magnetic coupling can be tuned from ferromagnetic to ferrimagnetic by changing the number of gold atoms coated on its surface. We found that 26 gold atoms are needed to fully cover a Mn(4) cluster. When partially coated, the system exhibits ferromagnetic coupling with a total magnetic moment of 18 micro(B) and it becomes ferrimagnetic with a moment of 8 micro(B) when fully coated. This magnetic cross-over is caused by the shrinking of the Mn-Mn bond length, suggesting that the magnetic properties of a Mn(4) cluster can be tuned by controlling the surface coverage.
authors.affiliation: School of Physical Science and Technology, Southwest University, Chongqing 400715, China. qwang@vcu.edu
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: Q
authors.initials: Q
authors.lastname: Sun
authors.forename: P
authors.initials: P
authors.lastname: Jena
authors.forename: Y
authors.initials: Y
authors.lastname: Kawazoe