Access

Letter

Nature 439, 825-827 (16 February 2006) | doi:10.1038/nature04499; Received 22 July 2005; Accepted 29 November 2005

Open Innovation Challenges

A spin triplet supercurrent through the half-metallic ferromagnet CrO2

R. S. Keizer1, S. T. B. Goennenwein1,4, T. M. Klapwijk1, G. Miao2,3, G. Xiao3 & A. Gupta2

  1. Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, 2628 CJ, Delft, The Netherlands
  2. MINT Center, University of Alabama, Tuscaloosa, Alabama 35487, USA
  3. Physics Department, Brown University, Providence, Rhode Island 02912, USA
  4. †Present address: Walther-Meis zligner-Institut, Bayerische Akademie der Wissenschaften,Walther-Meis zligner-Stras zlige 8, D-85748, Garching, Germany

Correspondence to: R. S. Keizer1T. M. Klapwijk1 Correspondence and requests for materials should be addressed to R.S.K. (Email: r.s.keizer@tnw.tudelft.nl) or T.M.K. (Email: t.m.klapwijk@tnw.tudelft.nl).

Top

In general, conventional superconductivity should not occur in a ferromagnet, though it has been seen in iron under pressure1. Moreover, theory predicts that the current is always carried by pairs of electrons in a spin singlet state2, so conventional superconductivity decays very rapidly when in contact with a ferromagnet, which normally prohibits the existence of singlet pairs. It has been predicted that this rapid spatial decay would not occur if spin triplet superconductivity could be induced in the ferromagnet3, 4. Here we report a Josephson supercurrent through the strong ferromagnet CrO2, from which we infer that it is a spin triplet supercurrent. Our experimental set-up is different from those envisaged in the earlier predictions, but we conclude that the underlying physical explanation for our result is a conversion from spin singlet pairs to spin triplets at the interface. The supercurrent can be switched with the direction of the magnetization, analogous to spin valve transistors, and therefore could enable magnetization-controlled Josephson junctions.

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.

NEWS AND VIEWS

Hybrid devices Mixing superconductivity and magnetism

Nature Materials News and Views (01 Nov 2004)

Human therapeutic proteins from silkworms

Nature Biotechnology Research News (01 Jan 2003)

See all 4 matches for News And Views