Peter Grünberg


Interview, December 2007

Interview with the 2007 Nobel Laureates in Physics Albert Fert and Peter Grünberg, 6 December 2007. The interviewer is Adam Smith, Editor-in-Chief of

The Laureates talk about their research, how they became physicists (3:33), the challenges faced by today’s young physicists (8:28), the mentors who influenced their careers (13:30), the marvel of physics (17:10), giant magnetoresistance and its applications (20:01), and life after the Nobel Prize (28:36).

Nobel Minds 2007

The 2007 Nobel Laureates met at the Bernadotte Library in Stockholm on 9 December 2007 for the traditional round-table discussion and TV show ‘Nobel Minds’. The show was hosted by BBC presenter Sarah Montague. The Laureates discussed topical issues of global concern, and also answered questions submitted by visitors to and

Your questions to Peter Grünberg

Here, Peter Grünberg answers additional questions submitted by visitors to

Read the questions and answers

Interview, October 2007

Telephone interview with Peter Grünberg immediately following the announcement of the 2007 Nobel Prize in Physics, 9 October 2007. The interviewer is Adam Smith, Editor-in-Chief of

Interview transcript

[Kosta Schinarakis] – Kosta Schinarakis, hallo.

[Adam Smith] – Hello, may I speak to Peter Grünberg please?

[KS] – It’s very complicated at the moment, he’s drinking champagne with his colleagues.

[AS] – I can imagine.

[KS] – Who are you?

[AS] – My name is Adam Smith and I’m calling from the Nobel Foundation’s website,

[KS] – So, one moment. Just, I see Mister Grünberg, he’s … one moment.

[AS] – Yes.

[Peter Grünberg] – Hello, here’s Peter Grünberg.

[AS] – Oh, hello, Professor Grünberg, this is Adam Smith from the Nobel Foundation’s website, We have a tradition of recording very brief telephone interviews with new Laureates for the archives …

[PG] – Yes, OK.

[AS] – Thank you very much. Well first of all, of course, many, many congratulations on the Prize.

[PG] – Thank you.

[AS] – Where were you when you heard the news?

[PG] – I was, in fact, in my office already. Of course, and then there were many people coming and congratulate me.

[AS] – I gather I just interrupted you drinking champagne, so I apologize.

[PG] – Yes, right, I still have the glass of champagne, not quite emptied, before me.

[AS] – Oh, splendid, OK. So, the award is for your discovery, together with Albert Fert, of giant magnetoresistance …

[PG] – Right.

[AS] – … how did you become aware that Albert Fert had made the same discovery that you had made?

[PG] – Oh that was on a conference in France, in 1988, we had the ICM, which is the main magnetism conference, in France, in Paris, and after that we had the ICMFS, in Le Creusot, and then both of us gave a talk and after the talk we stated “Yes, we obviously found the same kind of an effect.” We found it in double-layer structure, with two magnetic films, and Albert had a multi-layer structure, and therefore it was stronger in his case, but we realized that it is the same kind of physics which leads to this effect in the two different systems. And so one can really locate it to the conference in Le Creusot in 1988, when we heard from each other for the first time.

[AS] – And it must have been amazing to find that the two of you had the same results. What was your reaction to this?

[PG] – Well in a way, I think, the history before was in a way similar. Because two years before that time I had discovered the antiferromagnetic interlayer exchange coupling and I reported on that in various conferences and Albert Fert heard one of these talks and decided that, for the kind of physics he is doing, namely magnetoresistance effects in diluted alloys, that would be an interesting configuration to investigate this effect also in the layered structures with the antiferromagnetic exchange coupling. So via this kind of coupling we came into the same kind of area in physics.

[AS] – Right. So your research paths were linked before the actual discovery.

[PG] – Yes, so it was in fact linked before really, only that I didn’t know that he was looking also now into this coupling phenomena.

[AS] – And were you looking for the effect that you discovered, or was it a surprise discovery, when you were looking for something else?

[PG] – Well we did the experiment because we expected something. I expected that electrons which penetrate into a layer with the opposite spin direction as to the magnetization would be differently scattered at the interface than an electron which is parallel to the magnetization. And based on this expectation then we expected that there should be a difference for the resistance between the parallel and the anti-parallel magnetization alignment in such double-layered structures.

[AS] – Right.

[PG] – So that’s why we started to work on this and made proper samples and so on.

[AS] – Yes, for those who find the quantum mechanical properties we’re describing very complicated could one make the analogy to say that this is a little bit like polaroid filters for light? That if you cross the polaroids you don’t get light passing through.

[PG] – Yes, yes, very much so, yes. This describes it very well.

[AS] – And now the applications of giant magnetoresistance have been many and various. Which ones excite you the greatest?

[PG] – At the moment, well, in fact we were wondering and discussing the application in hard disk drives so much and I think economically this really was a breakthrough for the hard disk drives. But since we are discussing that now for many years, I’m not so excited any more about this. But I found other applications where the giant magnetoresistance comes nicely very in and that is for the detection of genetic material, which you can separate by magnetic separation. You can attach antigenes to antibodies, you can attach the antibodies to so-called magnetic beads and via magnetoresistive sensors you can then detect genetic material. And this is a topic which is very broad and if it works it has many, many applications. It works together with magnetic nanoparticles which are superparamagnetic. And so that’s an application which is also discussed now for some time and famous labs also zero-in on this topic and treat that.

[AS] – That’s fascinating, and so I imagine you had no idea when you were working on this in the late eighties that your discoveries in physics would extend to biology?

[PG] – No, no. In fact it’s a funny situation in this because we are using magnetic nanoparticles in that, magnetic nanoparticles which are superparamagnetic. And we are used always from the hard disk drive so that superparamagnetism is, so to say, the enemy of application, and one tries to avoid superparamagnetism. And here, in this area, in these small magnetic particles it’s welcome, we want superparamagnetism. So this is another aspect which leads over into other areas in magnetism and the magnetism of very fine particles, nanoparticles and so on, and superparamagnetism.

[AS] – Right, very exciting. And your plans for the rest of the day then? How do you intend to continue your celebrations of the news?

[PG] – Well certainly, what I know, is that at 2 o’clock we will have a press conference here, and we will talk much more about all these effects and why it is important. I think it is important in the context really of computers. Computers have really changed our lives in the last few decades. I really enjoy very much to browse in the internet and get so many informations. Daily one can really experience the advantages of having computers and for the computer it was also a very important contribution, for the storage capacity of computers. So in this context I found this also a very important contribution.

[AS] – Yes.

[PG] – But not only this, but, as I just said about these genetic investigations, I think there it also plays an important role.

[AS] – Yes, the Prize very clearly links the discovery to the greatest benefit of mankind. It’s a very nice, and understandable, example.

[PG] – Yes.

[AS] – So, thank you very much for sparing the time to talk to us. When you come to Stockholm in December to receive the award, we will speak further I hope.

[PG] – Good, I’m looking forward.

[AS] – Thank you very much indeed.

[PG] – OK, thank you too.

[AS] – And congratulations, bye, bye.

[PG] – Thank you, bye, bye.

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