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

Basini, M.; Sanna, S.; Orlando, T.; Bordonali, L. 1; Cobianchi, M.; Arosio, P.; Mariani, M.; Peddis, D.; Bonanni, V.; Mathieu, R.; Kalaivani, T.; Singh, G.; Larionova, J.; Guari, Y.; Lartigue, L.; Lascialfari, A.
1 Institut für Mikrostrukturtechnik (IMT), Karlsruher Institut für Technologie (KIT)


By means of muon spin relaxation measurements we unraveled the temperature spin dynamics in monodisperse maghemite spherical nanoparticles with different surface to volume ratio, in two samples with a full core (diameter D∼4 and D∼5nm) and one with a hollow core (external diameter D∼7.4nm). The behavior of the muon longitudinal relaxation rates as a function of temperature allowed us to identify two distinct spin dynamics. The first is well witnessed by the presence of a characteristic peak for all the samples around the so-called muon blocking temperature T$_{B}^{μ+}$. A Bloembergen-Purcell-Pound (BPP)-like model reproduces the experimental data around the peak and at higher temperatures (20<T<100K) by assuming the Néel reversal time of the magnetization as the dominating correlation time. An additional dynamic emerges in the samples with higher surface to volume ratio, namely, full 4 nm and hollow samples. This is witnessed by a shoulder of the main peak for T<20K at low longitudinal field (μ$_{0}$H≈15mT), followed by an abrupt increase of the relaxation rate at T<10K, which is more evident for the hollow sample. These unusual anomalies of the longitudinal relaxation rate for T<T$_{B}^{μ+}$ are suggested to be due to the surface spins’ dynamical behavior. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000126977
Veröffentlicht am 25.01.2021
DOI: 10.1103/PhysRevB.102.195424
Zitationen: 4
Web of Science
Zitationen: 4
Zitationen: 4
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Mikrostrukturtechnik (IMT)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 2469-9950, 2469-9969
KITopen-ID: 1000126977
HGF-Programm 43.22.03 (POF III, LK 01) Printed Materials and Systems
Erschienen in Physical review / B
Verlag American Physical Society (APS)
Band 102
Heft 19
Seiten Art.Nr. 195424
Vorab online veröffentlicht am 19.11.2020
Nachgewiesen in Dimensions
Web of Science
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