Low Temperature Physics: 38, 657 (2012); https://doi.org/10.1063/1.4736614 (5 pages)
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
Received February 13, 2012
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;
Key words: cluster glass, exchange bias, phase separation, relaxation.