What are you looking for ?
Infinidat
Articles_top

R&D: Spintronics Resetting Future of HAMR

Examined thin films of Dysprosium-Cobalt sputtered onto nanostructured membrane at BESSY II.

A Helmholtz-Zentrum Berlin (HZB) team has examined thin films of Dysprosium-Cobalt sputtered onto a nanostructured membrane at BESSY II.

The nanostructured membrane has a honeycomb pattern
with nanoholes of 68nm in diameter.
The nanoholes pin down the magnetic domains.

(Credit: HZB)

HZB_1

They showed that new patterns of magnetization could be written in a quick and easy manner after warming the sample to only 80°, which is a much lower temperature as compared to conventional Heat Assisted Magnetic Recording systems. This paves the way to fast and energy efficient ultrahigh density data storage. The results are published now in the new journal Physical Review Applied.

To increase data density further in storage media, materials systems with stable magnetic domains on the nanoscale are needed. For overwriting a specific nanoscopic region with new information, a laser is used to heat locally the bit close to the so called Curie-Temperature, typically several hundred degrees Celsius. Upon cooling, the magnetic domain in this region can be reoriented in a small external magnetic field, known as HAMR. In industry, Iron-Platinum materials are currently used as magnetic media for the development of such HAMR-data storage devices.

A thin film of Dysprosium-Cobalt (green) has been sputtered on top
of the membrane, resulting in an array of antidots. The magnetic moments of DyCo
5
are perpendicular to the plane and stable against external magnetic fields.
A laser pulse can be used to locally increase the temperature of individual bits.

(Credit: HZB)

HZB_2

Moderate heating up to 80° does tilt the magnetic moment
associated to a single bit into the plane. Upon cooling to room temperature,
the magnetic moment stays in plane, until it is overwritten by a magnetic writing head.

(Credit: HZB)
HZB_3

Magnetic signals mapped at BESSY II before and after heating
A HZB team has now examined a new storage media system of Dysprosium and Cobalt, which shows key advantages with respect to conventional HAMR materials: A much lower writing temperature, a higher stability of the magnetic bits, and a versatile control of the spin orientation within individual magnetic bits. They achieved this by sputtering a thin film of Dysprosium and Cobalt onto a nanostructured membrane. The membrane was produced by scientific cooperation partners at the Institute of Materials Science of Madrid. The system shows a honeycomb antidot pattern with distances of 105nm between nanoholes, which are 68nm in diameter. These nanoholes act themselves as pinning centers for stabilizing magnetic wall displacements. The magnetic moments of DyCo5 are perpendicular to the plane and stable against external magnetic fields.

Energy efficient process
HZB-physicist Dr. Jaime Sánchez-Barriga and his team could demonstrate that warming the system to only 80 degrees Celsius is sufficient to tilt the magnetic moments in the DyCo5 film parallel to the surface plane. With measurements at the PEEM and XMCD instruments at BESSY II they could map precisely the magnetic signals before, during and after warming. After cooling to room temperature it is then easy to reorient the magnetic domains with a writing head and to encode new information.

This process in DyCo5 is energy efficient and very fast”, states Dr. Florin Radu, co-author of the study.

Our results show that there are alternative candidates for ultrahigh density HAMR storage systems, which need less energy and promise other important advantages as well”, adds Sánchez-Barriga.

Publication: Ferrimagnetic DyCo5 nanostructures for bits in heat-assisted magnetic recording. Doi.

Article :
Physical Review Applied has published an article written by A. A. Ünal, S. Valencia, F. Radu1, D. Marchenko, Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany, K. J. Merazzo, M. Vázquez, Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain, and J. Sánchez-Barriga1, Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany.

(a) SEM and (b) x-ray photoelectron emission microscopy (XPEEM) images
of the hexagonal lattice antidot array of 68-nm pore size and 105nm
separation between pore centers. XAS spectra of (c) Co and (d) Dy elements
at their     and     edges, as obtained from XPEEM energy scans
extracted in the field of view seen in (b) using a x-ray beam
of horizontal linear polarization
.

HZB

Abstract: “Increasing the magnetic data recording density requires reducing the size of the individual memory elements of a recording layer as well as employing magnetic materials with temperature-dependent functionalities. Therefore, we predict that the near future of magnetic data storage technology involves a combination of energy-assisted recording on nanometer-scale magnetic media. We present the potential of heat-assisted magnetic recording on a patterned sample; a ferrimagnetic alloy composed of a rare-earth and a transition metal DyCo5, which is grown on a hexagonal-ordered nanohole array membrane. The magnetization of the antidot array sample is out-of-plane oriented at room temperature and rotates towards in plane upon heating above its magnetic anisotropy reorientation temperature (TR) of 350 K, just above room temperature. Upon cooling back to room temperature (below TR), we observe a well-defined and unexpected in-plane magnetic domain configuration modulating with 45nm. We discuss the underlying mechanisms giving rise to this behavior by comparing the magnetic properties of the patterned sample with the ones of its extended thin-film counterpart. Our results pave the way for future applications of ferrimagnetic antidot arrays of superior functionality in magnetic nanodevices near room temperature.”

Articles_bottom
AIC
ATTO
OPEN-E