Dresden 2020 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 10: Multiferroics and Magnetoelectric Coupling II (joint session MA/KFM)

KFM 10.3: Talk

Wednesday, March 18, 2020, 15:30–15:45, HSZ 401

Signatures of electric dipoles in zig-zag spin chain β-TeVO₄ — Martina Dragičević¹, Željko Rapljenović¹, David Rivas Góngora¹, Mirta Herak¹, •Tomislav Ivek¹, Matej Pregelj², Andrej Zorko², Helmuth Berger³, and Denis Arčon^2,4 — ¹Institute of Physics, Zagreb, Croatia — ²Jožef Stefan Institute, Ljubljana, Slovenia — ³Ecole polytechnique fédérale de Lausanne, Lausanne, Switzerland — ⁴Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia

Even though non-composite magnetoelectric materials appear to be rare, one promising way to achieve magnetoelectric effect is through spiral magnetic orders which can break the space inversion symmetry and allow electric dipoles to form. In this work we present the dielectric response of single crystal quasi-1D quantum magnet β-TeVO₄ at low temperatures and in the presence of external magnetic field. This zig-zag spin chain system with frustrated anisotropic interactions has a complex phase diagram: at T_N1 = 4.65 K the paramagnetic phase gives way to an incommensurate spin-density wave; below T_N2 = 3.28 K a superposition of two spin-density waves is observed with differing wave vectors, the so-called spin stripe phase; finally, at the low temperature of T_N3 = 2.28 K their two wave vectors coincide and a vector chiral ground state is established. Most interestingly, at T_N3 there are tantalizing experimental indications of emergent electric dipoles. The magnetic phase diagram will be discussed in the context of dielectric properties and of ground state as a potentially multiferroic phase.