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Exclusive Interview With Nobel Price Albert Fert, Inventor of GMR

Technology able to increase drastically capacity of HDDs

fertFrench Albert Fert (see picture), 77, and German Peter Grünberg were the only two scientists to get, together, a Nobel price on a storage technology, GMR, able to increase drastically the capacity of HDDs.



StorageNewsletter.com: In brief, what is Giant MagnetoResistance (GMR) you invented with Peter Grünberg in 1988 to get awarded together the 2007 Nobel price in physics?
Fert: GMR is a property of magnetic multi-layers. A magnetic multi-layer is a film stacking layers of various magnetic and non-magnetic materials, for example alternately cobalt and copper layers.
The GMR is the following property: when the magnetizations of the magnetic layers are randomly oriented, the electrical resistance of these films is very large; this resistance decreases considerably when a small magnetic fields aligns the magnetizations, and this drop of the electrical resistance in the presence of a magnetic fields, is what you use to read the magnetic bits in the hard disks of today.

Who was really the fist one to discover GMR?
The roots of the GMR are in my previous work on the influence of the magnetism of the electrons on the electrical conduction in magnetic materials like cobalt or iron. The idea of the GMR was already in my PhD eighteen years before the discovery. But at this time the technology did not exist to fabricate multi-layers with thin enough layers. In the beginning of the eighties it became possible to prepare these multi-layers, this led me to the discovery of the GMR. And at the same time, in Germany, Peter Grünberg made the same discovery.

What was the impact of GMR on HDDs?
The first application was magnetic field sensors for the car industry. It happened only three years after the discovery. But the most commercially important application was for the hard disk drives.
You have a GMR sensor in the read head of the hard disk and the resistance of this sensors drops strongly in the presence of the very small magnetic field generated by the magnetic bits. The sensitivity of the GMR to detect very small field led to the detection of very small bits and to an increase of the capacity of the disks, by a factor of thousand.
GMR being able to detect much smaller bits, it is possible to put a larger number of bits in the same area.

Are you also at the origin of Tunnel Magneto Resistance?
No I’m not at the origin of the TMR, but it’s a similar effect. It’s again a multi-layer, but the two magnetic layers are separated by a thin insulating layer of oxide of magnesium generally. The effect is the same, the electrical resistance of what is called a “tunnel junction” drops when the magnetizations becomes parallel. The only difference is that the transport of electrons is not by the usual electrical conduction, it is a transport of electrons across the insulating layer by the quantum mechanism called “tunneling“. The first results were obtained in Japan and at the MIT around 1970.  

Now we are reaching some limits in areal density with GMR. Which technology will be able to go ahead?
We are not exactly at the limit. According to what I know about some companies’ plans in California, there will be an increase of the information capacity by a factor of five in the next generation of disk using what is called the CPP – GMR : the GMR with the Current, Perpendicular to the Plane. To go beyond, other technologies will be necessary.
Beyond the hard disk, there will be other type of technologies based on other types of effects, racetrack memories, memories with skyrmions. The skyrmions are particule-like magnetic configuration that can be as small as a few nanometers.These configurations are stabilized by topological properties and can be moved very easily by an electric field. They could represent the ultimate small size in which the information can be stored.

When can you get that ?
We are in the stage of fundamental research at this point. The recent progress we have accomplished in my group is obtaining these small skyrmions at room temperature.

Were you contacted by HDD manufacturers when you got your Nobel prize?
I was contacted well before the Nobel prize. The Nobel came 20 years after the discovery but I was in contact with IBM storage just 3 month after the first announcement of the discovery. (laugh) The timescale of the Nobel foundation is much longer.
In France, there was also a development of read head based on GMR by the company Thomson-CSF but the effort was stopped after the reorganization of the Thomson group.

Did you register patents on the subject?
I registered a patent with the company Thomson, but Grünberg was faster than us. The first patent was from Peter Grünberg.

So you never got royalties on your invention. Was it the same for Peter Grünberg?
I got royalties from other discoveries. The GMR was not the only result. But the royalties from the GMR itself went to Peter. He sold the patent to IBM quite rapidly. I can’t remember how much he got exactly.

How much did you earn for your Nobel price?
About half a million of euros.

What is your current job?
I am a researcher in physics. I work in a joint laboratory between the CNRS and the company Thalès. We are located on the site of Thalès Research and Technology, in Palaiseau.

How many children?

Your hobbies?
I will say music, jazz music, also movies, las pelliculas de Pedro Almodovar being among my favourite movies. When I was younger I was also a rugby player. I played rugby when I was in my Toulouse High School, I played in Grenoble University Club, and during my post-doc at the University of Leeds in England I played in the team of the town of Otley.
Years later, just after the announcement of the Nobel prize, the people of Leeds sent me a copy of an article in a British newspaper with a wonderful title: “A former Otley rugby player wins Nobel Prize.


Editors' note:

The first hard disk drive using Giant MagnetoResistive (GMR) heads was the IBM Deskstar 16GP Titan, released in 1997, according to Disk/Trend. Capacity was 16.8GB into four 3.5-inch disks. Today the highest HDD capacity is 10TB or 600X more.

After GMR, perpendicular magnetic recording (PMR) became commercially available in 2005, when Toshiba's Storage Device Division announced shipment of the world's first HDD using PMR technology on an 1.8-inch unit.

Then there was TMR (Tunnel MagnetoResistance) and SMR (Shingled Magnetic Recording).

Pattern media and HAMR (Heat-Assisted Magnetic Recording) are expected in the future to increase areal density.

Read also:
The Giant Magnetoresistive Head: A giant leap for IBM Research
Magnetoresistive (MR) heads and the earliest MR head-based disk drives: Sawmill and Corsair
State-of-the-Art Magnetic Hard Disk Drives
Magnetic Recording by Stella Z. Wu, Seagate Technology
Giant magnetoresistance (Wikipedia)