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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 (R_1−xY_x)₂Ti₂O₇ with R = Ho,Dy — •Jean-Francois Welter¹, Simon Scharffe¹, Gerhard Kolland¹, Martin Valldor^1,2, Victoria Cho¹, Peter Laschitzky¹, and Thomas Lorenz¹ — ¹II. 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 (R_1−xY_x)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 (κ_ph) and magnetic (κ_mag) contributions. In both R₂Ti₂O₇ compounds, κ_mag is sizable and can be attributed to magnetic monopole excitations[2]. We find that κ_mag is more pronounced in Dy₂Ti₂O₇ and that the field dependences of κ_ph 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).