Dec 8 – 10, 2020 Online only
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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
Online event

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Talk UM: Quantum Phenomena MLZ Users 2020 - Quantum Phenomena


Anton Kulbakov


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


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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