Speaker
Philipp Schmakat
(Physik-Department E21, Technische Universität München, D-85748 Garching, Germany)
Description
At the neutron imaging beam line ANTARES at FRM II, Munich, we have recently developed the Neutron Depolarisation Imaging (NDI) technique [1,2]. The NDI method, which is a combination of neutron radiography and polarisation analysis, allows mapping of variations of magnetic properties over a sample on a length scale of about 300 µm. These may, for instance, result from variations of the chemical composition of the sample [3]. A closed cycle cryostat in combination with a 3He/4He dilution insert has enabled us to reach temperatures as low as 75 mK in such measurements. A study on the metallurgically inhomogenous Kondo lattice system CePd(1-x)Rh(x) [4,5] has been performed to demonstrate the potential of the NDI technique at such low temperatures. Additional magnetic fields applied at the sample position allowed us to identify spin glass behaviour in CePd(1-x)Rh(x) at low temperatures for moderate Rh concentration x. In our contribution we will discuss the experimental technique as well as its application to disordered, ferromagnetic materials that undergo quantum phase transitions.
References:
[1] M. Schulz et al., "A polarizing neutron periscope for neutron imaging", Nucl. Instr. and Meth. in Phys. Res. A, Vol. 605, 2009, p.43-46
[2] M. Schulz et al., "Neutron depolarisation imaging: Stress measurements by magnetostriction effects in Ni foils", Physica B, Vol. 406, 2011, p.2412-2414
[3] C. Pfleiderer et al., "Search for Electronic Phase Separation at Quantum Phase Transitions", J. Low Temp. Phys., Vol. 161, 2010, p.167-181
[4] T. Westerkamp et al., "Kondo-Cluster-Glass State near a Ferromagnetic Quantum Phase Transition", Phys. Rev. Lett., Vol. 102, 2009, 206404.
[5] J. G. Sereni et al., "Ferromagnetic quantum criticality in the alloy CePd1−xRhx", Phys. Rev. B, Vol. 75, 2007, 024432
Primary author
Philipp Schmakat
(Physik-Department E21, Technische Universität München, D-85748 Garching, Germany)
Co-authors
Christian Pfleiderer
(Physik-Department E21, Technische Universität München, D-85748 Garching, Germany)
Christoph Geibel
(Max-Planck-Institut für Chemische Physik fester Stoffe, D-01187 Dresden, Germany)
Manuel Brando
(Max-Planck-Institut für Chemische Physik fester Stoffe, D-01187 Dresden, Germany)
Micha Deppe
(Max-Planck-Institut für Chemische Physik fester Stoffe, D-01187 Dresden, Germany)
Michael Schulz
(Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), D-85748 Garching, Germany)
Peter Böni
(Physik-Department E21, Technische Universität München, D-85748 Garching, Germany)
