Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 68: Poster 5

MA 68.17: Poster

Freitag, 24. März 2017, 09:30–13:00, P2-OG4

Dielectric spectroscopy of doped spin ice — •Lena Klaas, C. P. Grams, J. Engelmayer, T. Lorenz, and J. Hemberger — II. Physikalisches Institut, Universität zu Köln, Cologne, Germany

Spin-ice systems have raised strong interest due to the emergence of magnetic monopoles. In Dy₂Ti₂O₇ the condensation of these excitations was demonstrated to undergo a first-order phase transition with a critical endpoint at T=0.36 K and µ₀ H=1 T in crystallographic [111]-direction. Furthermore, magnetic monopoles also carry electric dipoles[1], making their dynamics accessible by dielectric spectroscopy. Measurements on Dy₂Ti₂O₇ have demonstrated unusual fluctuation dynamics above the critical temperature, a critical speeding-up[2]. To investigate the influence of defects on this relaxation dynamics we studied the system (Dy_1−xY_x)₂(Ti_1−yZr_y)₂O₇ with different doping levels of non-magnetic Y³⁺- or Zr⁴⁺-ions. Here, we show dielectric measurements up to frequencies of 1 MHz and down to temperatures of 0.2 K and demonstrate that critical speeding-up is observed for Y doping with x up to 10% above which the spin-ice behaviour is suppressed[3].

[1] D. I. Khomskii, Nat. Commun. 3, 1-13. (2012)

[2] C. P. Grams, M. Valldor, M. Garst, and J. Hemberger,
Nat. Commun. 5, 4853. (2014)

[3] S. Scharffe, O. Breunig, V. Cho, P. Laschitzky, M. Valldor,
J. F.Welter, and T. Lorenz, Phys. Rev. B 92, 180405 (2015)