Seminarium Oddziału Badań Magnetyków

13:30 środa, 24-04-19
sala nr 6 (bud. II)

Single chain magnets

dr hab. Michał Rams

Instytut Fizyki Uniwersytetu Jagiellońskiego

Single chain magnet (SCM) behavior may be observed in crystals in which the exchange interaction between spins creates a quasi-1-dimensional system. Despite the lack of a long-range magnetic order at a finite temperature, SCMs may exhibit a remanent magnetization due to slow magnetic relaxation below a blocking temperature. As shown by Glauber in 1963, the relaxation time of ferromagnetically coupled chain of Ising spins follows the Arrhenius law with an activation energy barrier. The first experimental observation of such a behaviour was found 40 years later, and till today only few such examples exist. During the talk I will focus on magnetic properties of the family of compounds built of MnIII and FeIII (or OsIII) ions linked into chains by cyanide bridges -CN-. These compounds appear to be very good SCMs. The parameters related to the SCM behaviour will be discussed basing on the experimental data analysis. This includes (1) Ising like anisotropy, (2) strong exchange interaction within the chains, (3) weak inter-chain interaction, (4) the energy barrier of relaxation processes and their mechanism, (5) the influence of defects in the crystal structure. As a second example, the properties of Co(NCS)2(L)2 chain compounds that we currently study, shall be presented.

[1] M. Rams et al., Inorg. Chem. 53, 10291.
[2] E.V. Peresypkina et al., Chem. Commun. 50, 7150.    
[3] M. Rams et al., Phys. Chem. Chem. Phys. 19, 3232.

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