Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 71: Correlated Electrons: Poster Session

TT 71.44: Poster

Mittwoch, 18. März 2015, 15:00–18:00, Poster B

Heat Transport in dilute Spin-Ice Materials (R1−xYx)2Ti2O7 with R = Ho,Dy — •Jean-Francois Welter1, Simon Scharffe1, Gerhard Kolland1, Martin Valldor1,2, Victoria Cho1, Peter Laschitzky1, and Thomas Lorenz11II. Physikalisches Institut, Universität zu Köln, Germany — 2Max-Planck Institut für Chemische Physik fester Stoffe, Dresden, Germany

In the spin-ice materials R2Ti2O7 the magnetic R3+ ions form a network of corner-sharing tetrahedra. Recently, these materials attracted a lot of interest due to their groundstate degeneracy and the description of the low-energy excitations as magnetic monopoles[1]. In order to investigate the influence of the monpole propagation on the thermal conductivity κ, we dilute the spin-ice compounds with non-magnetic Yttrium. We synthesized single crystals of the series (R1−xYx)2Ti2O7 with 0≤ x≤ 0.75 using the floating-zone method. Comparing the thermal conductivity for different doping levels x, the total κ can be separated into a sum of phononic (κph) and magnetic (κmag) contributions. In both R2Ti2O7 compounds, κmag is sizable and can be attributed to magnetic monopole excitations[2]. We find that κmag is more pronounced in Dy2Ti2O7 and that the field dependences of κph are of opposite signs in the Dy- and Ho-based materials[3].

This work was supported by DFG via the project LO 818/2-1.

[1] Castelnovo et al., Nature 451, 42 (2008).

[2] Kolland et al., Phys. Rev. B, 86, 060402(R) (2012).

[3] Scharffe et al., J. Magn. Magn. Mater. (in press, arXiv:1406.4037).

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