Dec 8 – 10, 2020 Online only
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Europe/Berlin timezone

Destruction of long-range magnetic order in Cu$_2$GaBO$_5$ and Cu$_2$AlBO$_5$ ludwigites by an external magnetic field.

Dec 8, 2020, 4:15 PM
25m
Online event

Online event

Talk UM: Quantum Phenomena MLZ Users 2020 - Quantum Phenomena

Speaker

Anton Kulbakov

Description

Ludwigites are oxyborate compounds with the general formula $M_2^{2+}M^{\prime{\kern.5pt}3+}$BO$_5$. Their structure consists of low-dimensional zigzag walls with triangular motifs, making them an interesting playground for the realization of magnetic frustration on quasi-low-dimensional lattices. Of particular interest are copper ludwigites, in which the divalent transition-metal ion is Cu$^{2+}$, carrying a quantum spin 1/2, whereas the trivalent ion is nonmagnetic. Cu$_2$GaBO$_5$ and Cu$_2$AlBO$_5$ ludwigites have been careful characterized. Both compounds order antiferromagnetically with $T_\text{N}\approx4.1$ K and 3 K, respectively. Propagation vector for Cu$_2$GaBO$_5$ is $(0.45~0~-\!0.7)$, which was determined by diffraction measurement. We also collected $\mu$SR data as a function of temperature and weak longitudinal magnetic field. They indicate a decoupling in weak fields of about 2000 gauss, which suggests that the internal field experienced by the muon is unusually weak. On the other hand, magnetic field also induces a very fast depolarization of some small fraction of the muons, leading to a decrease in initial asymmetry, which is consistent with field-induced magnetic disorder. We also present inelastic neutron scattering measurements evidencing diffuse low-energy spin fluctuations associated with such a crossover. We suggest that these investigation help understand magnetic ordering and will be an additional step towards understanding the quantum spin system.

Primary author

Co-authors

Mr Oleg Janson (Leibniz Institute for Solid State and Materials Research IFW Dresden) Ms Evgeniya Moshkina (Kirensky Institute of Physics) Dr Rajib Sarkar (Institut für Festkörper- und Materialphysik, Technische Universität Dresden) Pavlo Portnichenko (TU Dresden) Dr Hubertus Luetkens (Paul Scherrer Institute) Fabiano Yokaichiya (Helmholtz-Zentrum-Berlin) Aleksandr Sukhanov (TU Dresden) Ms Rushana Eremina (Zavoisky Physical Technical Institute) Dr Philipp Schlender (Technische universität dresden) Astrid Schneidewind Dmytro Inosov (TU Dresden)

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