Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 27: Focus Session: Skyrmions meet Multiferroicity

MA 27.2: Vortrag

Mittwoch, 9. März 2016, 10:00–10:20, H25

Dielectric properties of the spin driven multiferroic linarite — •Alexander Ruff, Theresa Mack, Stephan Krohns, and Alois Loidl — Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Germany

In the last decade various mechanisms for coupled polar and magnetic ordering, so called multiferroicity, were discovered. Among various multiferroic systems, spin-driven ferroelectrics are in the scientific focus due to a close coupling of spin and charge leading to cross-link control of magnetic and electric order. These systems have noncollinear spin structures, e.g., magnetic phases with spiral or helical order. Thus, two canted neighbouring spins S_i and S_j allow for inverse Dzychaloshinskii-Moriya interaction resulting in spin-driven ferroelectric polarization P via P = Q x (S_i x S_j), where Q denotes the propagation vector of the spin spiral. Those complex magnetic phases often reveal unconventional magnetic behaviour, which can be found in frustrated quantum spin systems, like LiCuVO₄ or the naturally grown single crystal linarite, PbCuSO₄(OH)₂.

Here we present the dielectric properties as well as the ferroelectric polarization obtained via pyro- and magnetocurrent measurements, both in applied magnetic fields up to 9 T. Their analysis allows validating the theoretical prediction of P = Q x (S_i x S_j). Compared to prototypical LiCuVO₄, linarite crystallizes monoclinic leading to a more complex relation of crystallographic direction, ferroelectric polarization and spin spiral axis. Finally, we provide (H,T)-diagrams for the multiferroic phase of linarite.