Low Temperature Physics: 38, 657 (2012); https://doi.org/10.1063/1.4736614 (5 pages)
Физика Низких Температур: Том 38, Выпуск 7 (Июль 2012), c. 828-832    ( к оглавлению , назад )

Direct evidence of the low-temperature cluster-glass magnetic state of Nd2/3Ca1/3MnO3 perovskite

Alexander Feher1, Vladimir Desnenko2, Elena Fertman2, Sergiy Dolya2, Marcela Kajňaková1, and Anatoly Beznosov2

1P.J. Šafárik University in Košice, Faculty of Science, Park Angelinum 9, 04154 Košice, Slovakia

2B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Lenin Ave., Kharkov 61103, Ukraine
E-mail: fertman@ilt.kharkov.ua

Received February 13, 2012

Аннотация

In the presented study we have revealed a giant exchange bias in a colossal magnetoresistance Nd2/3Ca1/3MnO3 perovskite at low temperatures, evident of an intrinsic exchange coupling in this compound. The phenomena found confirms our previous assumption that the low-temperature magnetic structure of the compound is represented by small (nanosized) ferromagnetic clusters immersed within the charge-ordered antiferromagnetic matrix. Magnetic behavior of the Nd2/3Ca1/3MnO3 perovskite is consistent with a cluster-glass magnetic state and does not agree with a classical spin-glass state observed in a variety of disordered magnetic systems. We think that the cluster-glass magnetic behavior of Nd2/3Ca1/3MnO3 originates from the selforganized phase-separated state of the compound. The Cole-Cole analysis of the dynamic susceptibility at lowtemperatures has shown extremely broad distribution of relaxation times, indicating that spins are frozen at a “macroscopic” time scale. Slow relaxation of the zero-field-cooled magnetization has been experimentally revealed as well. This slow relaxation confirms the cluster-glass magnetic state of the compound. Two strongly different relaxation mechanisms were found: the first one is characteristic for temperatures below the freezing temperature Tg ~ 60 K, the second one is characteristic for higher temperatures.

PACS: 64.75.–g Phase equilibria;
PACS: 75.50.Lk Spin glasses and other random magnets;
PACS: 75.30.–m Intrinsic properties of magnetically ordered materials;
PACS: 75.47.Lx Magnetic oxides;
PACS: 77.22.Gm Dielectric loss and relaxation.

Ключевые слова: cluster glass, exchange bias, phase separation, relaxation.