29 January 2016

New record magnetic anisotropy in a molecular nanomagnet

Frequency-dependent EPR spectra (upper inset) and peak positions (main panel). Frequency-dependent EPR spectra (upper inset) and peak positions (main panel).

Scientists created a molecular nanomagnet based on a single nickel atom with record-high magnetic anisotropy — a quality that makes it a promising building block for applications like memory storage.

What did scientists discover?

A single atom has the potential to be the smallest unit of magnetic memory storage. But not just any atom, and not without just the right molecular environment. Only a few elements readily form magnetic compounds. And even for those atoms, the desired magnetic behavior can be undermined by the non-magnetic atoms surrounding it.

This is where so-called molecular nanomagnets come into play. By designing molecules containing just one or a handful of magnetic atoms, chemists have the ability to engineer the most important property for a magnetic memory. Called magnetic anisotropy, this property locks the north/south poles of the magnetic atom so that they point in only one of two directions. The magnetic anisotropy has to be strong in order to prevent reorientation of the magnet and, therefore, a loss of its stored information.

In this study, researchers created a strong nanomagnet by placing a single nickel atom in a very specific geometry within a molecule, fully maximizing its anisotropy. Using a technique called electron paramagnetic resonance (EPR), scientists measured a record-high anisotropy in this molecular nanomagnet, making it an ideal candidate for very high-density information storage.

Why is this important?

The miniaturization of data storage devices has led to a drastic reduction in the size of the basic unit of information, or bit. Currently companies produce devices that can pack one terabit of storage into one square inch, featuring bits that are just a few 100 square nanometers in size. Below this scale, molecular nanomagnets may play a crucial role in the future. With dimensions of less than one square nanometer, they have the potential for vastly greater storage density. So understanding and controlling the anisotropy of these materials can be vital for the future of computers, cell phones and other electronics. This work at the MagLab puts forth an important strategy for designing highly anisotropic molecular magnetic building blocks that could be used to develop a new generation of molecular-scale magnetic memory storage devices.

Who did the research?

K. E. R. Marriott1, C. Wilson1, M. Medarde2, S. T. Ochsenbein2, L. Bhaskaran3,4, S. Hill3,4, M. Murrie1

1University of Glasgow; 2Paul Scherrer Institute; 3National MagLab; 4Florida State University

Why did they need the MagLab?

THE TOOLS THEY USED

This research was conducted in the 35 T, 32 mm bore resistive magnet at the MagLab's DC Field Facility.

The MagLab’s Electron Magnetic Resonance Facility has substantial expertise in EPR, which provides a direct measure of magnetic anisotropy. The record-high magnetic anisotropy of the molecule studied in this experiment could only be measured in the very high magnetic fields available at the MagLab’s DC Field Facility.

Details for scientists

Funding

This research was funded by the following grants: G.S. Boebinger (NSF DMR-1157490); M. Murrie (EPSRC Ref. EP/J018147/1); S.T. Ochsenbein (EC FP7/2007-2013 grant # 290605); S. Hill (NSF DMR-1309463)


For more information, contact Stephen Hill.

Details

  • Research Area: Magnetism and Magnetic Materials
  • Research Initiatives: Materials
  • Facility / Program: EMR
  • Year: 2016
Last modified on 18 February 2016