Structure:

• WU Name: core_shell_nanoparticles
• Number of Spins: 32565
• Number of Spins over all: 32565
• CPU-time: ca. 4:00 hr (new system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

The interest of the scientific community in the magnetism of nanoparticles is strongly related to their potential application in high density data storage and spin electronics devices. Furthermore, fundamental questions are still opened to understand the static and dynamic aspects of the magnetic behavior of so-called core/shell nanoparticles.

As shown in the figure below, in such systems two different metals are arranged in a way that one metal is forming the core (red) of the nanoparticle and is seperated from the shell (yellow) which consists of a different metal. In between there is an interface layer where both kinds of metal interact. We assume an antiferromagnetic coupling within the core and a ferromagnetic coupling within the shell. Furthermore, the interfacial spins are coupled by a weak ferromagnetic coupling. We want to study a rather small nanoparticle which nevertheless consists of 32565 spins in total! For such a "monster calculation" we need the help of all spinhenge users!

Core/Shell nanoparticle consisting of 32565 spins. The core spins (shown in red) are made of a different metal than the shell spins (shown in yellow).

Structure: {Mo₇₂ Fe₃₀} - 30 paramagnetic Fe³⁺ ions (S = 5/2) embedded on the vertices of an icosidodecahedron

• WU Name: *fe30_map*_*
• Number of Spins: 30
• Number of Spins over all: 30
• CPU-time: ca. 1:05 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

In recent careful magnetic measurements of the Fe30 molecule done at the Ames Laboratory we have observed some strange features which could not have been detected before due to the sophisticated technique that one needs have at hand to perform such measurements. In order to understand these features we have proposed a new model description which takes into account small deviations from the ideal icosidodecahedron structure of the molecule and maps these onto the intra-molecular interaction scenario.

However, there is one unknown parameter which needs to be determined by subsequent comparison with the experimental data. In order to do so we need to perform a huge number of similar simulations which will be evaluated automatically and compared with the experiment! Using Spinhenge@home we distribute the whole calculation using several million work units! Our goal is to understand the reason for strange features recently detected in magnetic measurements of Fe30.


© 2005 H. Bögge