/ A. A. Kulbakov, R. Sarkar, O. Janson [et al.]> // Phys. Rev. B. - 2021. -
Vol. 103,
Is. 2. - Ст. 024447,
DOI 10.1103/PhysRevB.103.024447. - Cited References: 46. - We thank U. Nitzsche for technical assistance. This project was funded in part by the German Research Foundation (DFG) under Grant IN 209/9-1, via Project C03 of the Collaborative Research Center SFB 1143 (project-id 247310070) at the TU Dresden, and the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter—ct.qmat (EXC 2147, project-id 390858490). O.J. was supported by the Leibniz Association through the Leibniz Competition
. - ISSN 2469-9950
Перевод заглавия: Разрушение дальнего магнитного порядка во внешнем магнитном поле и связанная с ним спиновая динамика в людвигитах Cu2GaBO5 и Cu2AlBO5
Аннотация: The quantum spin systems Cu2M′BO5 (M′=Al,Ga) with the ludwigite crystal structure consist of a structurally ordered Cu2+ sublattice in the form of three-leg ladders, interpenetrated by a structurally disordered sublattice with a statistically random site occupation by magnetic Cu2+ and nonmagnetic Ga3+ or Al3+ ions. A microscopic analysis based on density-functional-theory calculations for Cu2GaBO5 reveals a frustrated quasi-two-dimensional spin model featuring five inequivalent antiferromagnetic exchanges. A broad low-temperature 11B nuclear magnetic resonance points to a considerable spin disorder in the system. In zero magnetic field, antiferromagnetic order sets in below TN≈4.1 K and ∼2.4 K for the Ga and Al compounds, respectively. From neutron diffraction, we find that the magnetic propagation vector in Cu2GaBO5 is commensurate and lies on the Brillouin-zone boundary in the (H0L) plane, qm=(0.45,0,−0.7), corresponding to a complex noncollinear long-range ordered structure with a large magnetic unit cell. Muon spin relaxation is monotonic, consisting of a fast static component typical for complex noncollinear spin systems and a slow dynamic component originating from the relaxation on low-energy spin fluctuations. Gapless spin dynamics in the form of a diffuse quasielastic peak is also evidenced by inelastic neutron scattering. Most remarkably, application of a magnetic field above 1 T destroys the static long-range order, which is manifested in the gradual broadening of the magnetic Bragg peaks. We argue that such a crossover from a magnetically long-range ordered state to a spin-glass regime may result from orphan spins on the structurally disordered magnetic sublattice, which are polarized in magnetic field and thus act as a tuning knob for field-controlled magnetic disorder.
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Держатели документа: Institut fur Festkorper- und Materialphysik, Technische Universitat Dresden, Dresden, 01069, Germany
Wurzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter - Ct.qmat, TU Dresden, Dresden, 01069, Germany
Institute for Theoretical Solid State Physics, IFW Dresden, Dresden, 01069, Germany
Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, Krasnoyarsk, 660036, Russian Federation
Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, Villigen PSI, CH-5232, Switzerland
Institute for Quantum Phenomena in Novel Materials, Helmholtz-Zentrum Berlin fur Materialen und Energie GmbH, Hahn-Meitner-Platz 1, Berlin, 14109, Germany
Max Planck Institute for Chemical Physics of Solids, Nothnitzer Str. 40, Dresden, 01187, Germany
Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of RAS, Sibirsky tract 10/7, Kazan, 420029, Russian Federation
Fakultat Chemie und Lebensmittelchemie, Technische Universitat Dresden, Dresden, 01069, Germany
Julich Center for Neutron Science at MLZ, Forschungszentrum Julich GmbH, Lichtenbergstra?e 1, Garching, 85748, Germany
Доп.точки доступа: Kulbakov, A. A.; Sarkar, R.; Janson, O.; Dengre, S.; Weinhold, T.; Moshkina, E. M.; Мошкина, Евгения Михайловна; Portnichenko, P. Y.; Luetkens, H.; Yokaichiya, F.; Sukhanov, A. S.; Eremina, R. M.; Schlender, P.; Schneidewind, A.; Klauss, H. -H.; Inosov, D. S.