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Magnetostriction of Samarium measured in high
magnetic Fields up to 33 T
M. Rottera, M. Doerrb, J. Brooksc,d, E.
Jobiliongd, A. Lindbauma, H. Müllere a Institute
of Physical Chemistry, University Vienna,
Währingerstr. 42, A-1090 Vienna, AUSTRIA b
Institute of Solid State Physics (IFP), TU
Dresden, D-01062 Dresden, GERMANY c Department of
Physics, Florida State University, Tallahassee,
FL 32306-5350, USA d National High Magnetic
Field Laboratory (NHMFL), Tallahassee, FL
32310-3704, USA b Institute of Solid State
Physics (IFP), TU Wien, A- 1040 Wien, AUSTRIA
Magnetostriction
Magnetism of Samarium

• TN109 K antiferromagnetic order of hexagonal
  sites
• T114 K antiferromagnetic order of quasicubic
  sites
• Moments are aligned parallel to c (easy axis)
• Hc30T spin flop transition of quasicubic
  moments

Magnetostriction
Thermal Expansion
M. Rotter et al. Phys Rev B, in print
Structure
Magnetostriction measurements on Sm were
performed up to the highest available steady
magnetic fields. We used a miniature capacitance
dilatometer in the Bitter magnets at NHMFL
(Tallahassee) and obtained a resolution of 10-6
in dl/l. Thermal expansion measurements were
performed using the same dilatometer in the VTI
of a standard lqHe cryostat.
Model of magnetostriction

• The magnetostriction in the standard model of
  rare earth magnetism results from ...
• the single ion crystal field (CEF) contribution
  and
• the two ion exchange interaction.
• M. Doerr, A. Lindbaum, M. Rotter Adv. Phys. 54
  (2005) 1.

Sm
At spinflop with Hc
Anisotropy in two Ion interactions
Summary

• Magnetostriction measurements are a powerful
  tool to study the magnetoelastic interactions and
  magnetic phase transitions in high fields.
• The magnetoelastic behavior of Samarium metal has
  been determined for the first time. A field along
  the hard direction has no effect on the crystal
  lattice (within the experimental error of dl/l
  10-6).
• The magnetostriction data can be interpreted by
  the exchange striction mechanism assuming
  anisotropy in the two ion interactions.

We acknowledge support by the Austrian Science
Foundation (FWF) within the projects P16957,
P17226 and by the Deutsche Forschungs-
gemeinschaft (DFG) within the Sonderforschungsbere
ich 463. A portion of this work was performed at
the National High Magnetic Field Laboratory,
which is supported by NSF Cooperative Agreement
No. DMR-0084173, by the State of florida, and by
the DOE.
Presented at LT 24, Orlando, 2005