By means of muon spin relaxation measurements we unraveled the temperature spin dynamics in monodis-perse maghemite spherical nanoparticles with different surface to volume ratio, in two samples with a full core(diameterD∼4andD∼5 nm) and one with a hollow core (external diameterD∼7.4 nm). The behaviorof the muon longitudinal relaxation rates as a function of temperature allowed us to identify two distinct spindynamics. The first is well witnessed by the presence of a characteristic peak for all the samples around theso-called muon blocking temperatureTμ+B. A Bloembergen-Purcell-Pound (BPP)-like model reproduces theexperimental data around the peak and at higher temperatures (20<100 K) by assuming the Néel reversaltime of the magnetization as the dominating correlation time. An additional dynamic emerges in the sampleswith higher surface to volume ratio, namely, full 4 nm and hollow samples. This is witnessed by a shoulderof the main peak forT<20 K at low longitudinal field (μ0H≈15 mT), followed by an abrupt increase ofthe relaxation rate atT<10 K, which is more evident for the hollow sample. These unusual anomalies ofthe longitudinal relaxation rate forT

Low-temperature anomalies in muon spin relaxation of solid and hollow γ−Fe2O3 nanoparticles: A pathway to detect unusual local spin dynamics / M. Basini, S. Sanna, T. Orlando, L. Bordonali, M. Cobianchi, P. Arosio, M. Mariani, D. Peddis, V. Bonanni, R. Mathieu, T. Kalaivani, G. Singh, J. Larionova, Y. Guari, L. Lartigue, A. Lascialfari. - In: PHYSICAL REVIEW. B. - ISSN 2469-9950. - 102:19(2020 Nov 19). [10.1103/PhysRevB.102.195424]

Low-temperature anomalies in muon spin relaxation of solid and hollow γ−Fe2O3 nanoparticles: A pathway to detect unusual local spin dynamics

Basini, M.;Arosio, P.;Bonanni, V.;
2020-11-19

Abstract

By means of muon spin relaxation measurements we unraveled the temperature spin dynamics in monodis-perse maghemite spherical nanoparticles with different surface to volume ratio, in two samples with a full core(diameterD∼4andD∼5 nm) and one with a hollow core (external diameterD∼7.4 nm). The behaviorof the muon longitudinal relaxation rates as a function of temperature allowed us to identify two distinct spindynamics. The first is well witnessed by the presence of a characteristic peak for all the samples around theso-called muon blocking temperatureTμ+B. A Bloembergen-Purcell-Pound (BPP)-like model reproduces theexperimental data around the peak and at higher temperatures (20<100 K) by assuming the Néel reversaltime of the magnetization as the dominating correlation time. An additional dynamic emerges in the sampleswith higher surface to volume ratio, namely, full 4 nm and hollow samples. This is witnessed by a shoulderof the main peak forT<20 K at low longitudinal field (μ0H≈15 mT), followed by an abrupt increase ofthe relaxation rate atT<10 K, which is more evident for the hollow sample. These unusual anomalies ofthe longitudinal relaxation rate forT
Settore FIS/03 - Fisica della Materia
PHYSICAL REVIEW. B
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/790732
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