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163 0 |
SM ISO690:2012 ZAHARKO, Oksana, CHRISTENSEN, Niels Bech, CERVELLINO, Antonio, TSURKAN, Vladimir, MALJUK, Andrey N., STUHR, Uwe, NIEDERMAYER, Ch, YOKAICHIYA, Fabiano, ARGYRIOU, Dimitri N., BOEHM, Martin, LOIDL, Alois. Spin liquid in a single crystal of the frustrated diamond lattice antiferromagnet CoAl2O4. In: Physical Review B - Condensed Matter and Materials Physics, 2011, vol. 84, p. 0. ISSN 1098-0121. DOI: https://doi.org/10.1103/PhysRevB.84.094403 |
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Physical Review B - Condensed Matter and Materials Physics | |
Volumul 84 / 2011 / ISSN 1098-0121 /ISSNe 1550-235X | |
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DOI:https://doi.org/10.1103/PhysRevB.84.094403 | |
Pag. 0-0 | |
Rezumat | |
We study the evidence for spin liquid in the frustrated diamond lattice antiferromagnet CoAl2O4 by means of single-crystal neutron scattering in zero and applied magnetic fields. The magnetically ordered phase appearing below TN=8 K remains nonconventional down to 1.5 K. The magnetic Bragg peaks at the q=0 positions are broad and their line shapes have strong Lorentzian contributions. Additionally, the peaks are connected by weak diffuse streaks oriented along the 111 directions. The observed short-range magnetic correlations are explained within the spiral spin-liquid model. The specific shape of the energy landscape of the system, with an extremely flat energy minimum around q=0 and many low-lying excited spiral states with q=111, results in thermal population of this manifold at finite temperatures. The agreement between the experimental results and the spiral spin-liquid model is only qualitative, indicating that microstructure effects might be important to achieve quantitative agreement. Application of a magnetic field significantly perturbs the spiral spin-liquid correlations. The magnetic peaks remain broad but acquire more Gaussian line shapes and increase in intensity. The 1.5 K static magnetic moment increases from 1.58 μB/Co at zero field to 2.08 μB/Co at 10 T. The magnetic excitations appear rather conventional at zero field. Analysis using classical spin-wave theory yields values of the nearest- And next-nearest-neighbor exchange parameters J 1=0.92(1) meV and J2=0.101(2) meV and an additional anisotropy term D=-0.0089(2) meV for CoAl2O4. In the presence of a magnetic field, the spin excitations broaden considerably and become nearly featureless at the zone center. |
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Cuvinte-cheie magnetism, Curie Temperature, Antiferromagnet |
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