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Spin dynamics in the single-ion magnet Er(W5O18)(2) (9-)

TitleSpin dynamics in the single-ion magnet Er(W5O18)(2) (9-)
Publication TypeJournal Article
Year of Publication2018
AuthorsMariani, M, Borsa, F, Graf, MJ, Sanna, S, Filibian, M, Orlando, T, Sabareesh, KPV, Cardona-Serra, S, Coronado, E, Lascialfari, A
JournalPhysical Review B
Date Published04
Type of ArticleArticle
ISBN Number2469-9950
Accession NumberWOS:000430380000002
Keywordschains, cluster, magnetization, molecule magnets, mu-sr, nanomagnets, physics, qubits, relaxation, Time, transitions

emperature. Both techniques yield a local field distribution of the order of 0.1-0.2 T, which appears to be of dipolar origin. On decreasing the temperature, a gradual loss of the H-1 NMR signal intensity is observed, a phenomenon known as wipe-out effect. The effect is analyzed quantitatively on the basis of a simple model which relies on the enhancement of the NMR spin-spin, T-2(-1) , relaxation rate due to the slowing down of the magnetic fluctuations. Measurements of spin-lattice relaxation rate T-1(-1) for H-1 NMR and of the muon longitudinal relaxation rate lambda show an increase as the temperature is lowered. However, while for the NMR case the signal is lost before reaching the very slow fluctuation region, the muon spin-lattice relaxation I can be followed until very low temperatures and the characteristic maximum, reached when the electronic spin fluctuation frequency becomes of the order of the muon Larmor frequency, can be observed. At high temperatures, the data can be well reproduced with a simple model based on a single correlation time tau = tau(omicron) exp(Delta /T) for the magnetic fluctuations. However, to fit the relaxation data for both NMR and mu(+) SR over the whole temperature and magnetic field range, one has to use a more detailed model that takes into account spin-phonon transitions among the Er3+ magnetic sublevels. A good agreement for both proton NMR and mu+SR relaxation is obtained, which confirms the validity of the energy level scheme previously calculated from an effective crystal field Hamiltonian.

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