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Muon Spin Rotation and Relaxation

In µSR spectroscopy muons are implanted in a sample and come to rest at interstitial sites. With measurement methods of nuclear physics one can follow the Larmor precession of the muons. This allows conclusions on internal magnetic fields in solids and their distribution and dynamics.

This animation shows the decay of a muon (re-animate by reloading this page) und the angular distribution of the emitted positron at maximum (a=1) and mean energy (a=1/3). It was kindly made available by Rod Macrae. The principle of µSR is based on the parity violation in the decay of pions and muons. First this gives us spin polarised muons, and second it correlates the emission direction of the decay positrons with the direction of the muon spin at the time of the decay. Given these facts the muon becomes a very sensitive probe for magnetic fields in matter. In muon spin rotation the precession of the implanted muons in an external transverse magnetic field is observed. In muon spin relaxation, on the other hand, one observes the decrease of the muon polarisation without an external field or in longitudinal fields. A comprehensive description of the µSR method can be found in the diploma thesis of Ernst Schreier (in German).

µSR measurements can only be performed at suitable facilities of so-called meson factories. We conduct our experiments at the following institutions:

The temperature range for experiments at the facilities there is 0.01 K to 1000 K. This is a selection of online available manuals for the facilities: Informationen on µSR and the facilities can also be found on the pages of other µSR groups.

Our research group uses µSR spectroscopy mainly in the study of the formation of magnetism in the elements and compound of the rare earths (4f transition metals). The research focuses on new materials like systems with heavy fermions, in which, for example, superconductivity and magnetism can coexist, or so-called Kondo metals, in which a strong competition prevails between the exchange interaction that produced magnetism and the Kondo coupling that suppresses it. These materials form a subgroup of the electronically highly correlated materials which include, among others, the high temperature superconductors. In cooperation with other research groups, complementary measurements are undertaken like specific heat, susceptibility and neutron diffraction measurements. Other research areas to which µSR is applied in the institute E15 include the study of spin glasses and the magnetic behaviour of oxidic spinels.

Research Group

Name Room Phone E-Mail
G. Michael Kalvius 2221 12501 / 12502 kalvius@physik.tu-muenchen.de
Andreas Kratzer 2246 12596 / 12513 kratzer@michi.e15.physik.tu-muenchen.de
Walter Potzel 2203 12508 Walter.Potzel@physik.tu-muenchen.de
Ernst Schreier 2207 12510 Ernst.Schreier@physik.tu-muenchen.de

Selected Publications

Diploma theses and Ph.D. theses

Journal articles and conference contributions

  • E. Frey, F. Schwabl, S. Henneberger, O. Hartmann, R. Wäppling, A. Kratzer and G.M. Kalvius,
    "Determination of the Universality Class of Gadolinium,"
    Phys. Rev. Lett. 79 (1997) 5142.
  • G.M. Kalvius, T. Takabatake, A. Kratzer, R. Wäppling, D.R. Noakes, S.J. Flaschin, F.J. Burghart, R. Kadono, I. Watanabe, A. Brückl, K. Neumaier, K. Andres, K. Kobayashi, G. Nakamoto and H. Fujii,
    "The influence of impurities and alloying in the Kondo semimetal CeNiSn as seen by µSR,"
    Hyperfine Interactions 104 (1997) 157.
  • H.-H. Klauß, M. Hillberg, W. Wagener, M. Birke, F.J. Litterst, E. Schreier, A. Kratzer, G.M. Kalvius, Y. Haga and T. Suzuki,
    "Local magnetic field and muon site in CeAs,"
    Hyperfine Interactions 104 (1997) 177.
  • A. Kratzer, C. Schopf, G.M. Kalvius, H.-H. Klauß, S. Zwirner and J.C. Spirlet,
    "µSR investigations of UX3 compounds,"
    Hyperfine Interactions 104 (1997) 181.
  • E. Lidström, R. Wäppling, S.F. Flaschin, G.M. Kalvius, A. Kratzer, D.T. Adroja, B.D. Rainford and A. Neville,
    "µSR studies of magnetic properties of CeRhSb and La0.1Ce0.9RhSb,"
    Hyperfine Interactions 104 (1997) 193.
  • M. Ekström, O. Hartmann, A. Marelius, R. Wäppling, E. Schreier, S. Henneberger, A. Kratzer and G.M. Kalvius,
    "µSR investigation of single crystalline dysprosium,"
    Hyperfine Interactions 104 (1997) 281.
  • S. Henneberger, E. Schreier, A. Kratzer, L. Asch, G.M. Kalvius, E. Frey, F. Schwabl, O. Hartmann, M. Ekström, R. Wäppling, F.J. Litterst and H.-H. Klauss,
    "µSR investigations of gadolinium in the paramagnetic regime near the ferromagnetic transition,"
    Hyperfine Interactions 104 (1997) 301.
  • E. Schreier, S. Henneberger, F.J. Burghart, A. Kratzer, G.M. Kalvius, O. Hartmann, M. Ekström and R. Wäppling,
    "High pressure µSR studies on single crystalline gadolinium,"
    Hyperfine Interactions 104 (1997) 311.
  • F.J. Burghart, W. Potzel, G.M. Kalvius, W. Schiessl, A. Kratzer, E. Schreier, A. Martin, M. Hillberg, R. Wäppling and D.R. Noakes,
    "Muons and muonium in Zn-spinels,"
    Hyperfine Interactions 106 (1997) 187.

 

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Location: Physics Department E15 - Fields of Research - µSR
Administration: Siegfried.Haslbeck@physik.tu-muenchen.de
Last update: 5.1.2000