Structural link to precursor effects

Novel dielectric anomalies due to spin-chains above and below Néel temperature in Ca3Co2O6

“…Therefore, with geometrical frustration triggering a lot of investigations by several experimental methods as well as by theoretical studies [see, for instance, Refs. 16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47 and articles cited therein] due to novelties of the magnetic properties of this compound, this material clearly is of great interest from the fundamental physics as well as from the applications angle.…”

Magnetic behavior of nanocrystals of the spin-chain systemCa3Co2O6: Absence of multiple steps in the low-temperature isothermal magnetization

“…The magnetic state in the range 10 -24 K is called "partially disordered antiferromagnetism (PDA)". Interesting anomalies have been found in many spectroscopic and bulk studies, including magnetodielectric coupling and thermopower from the applications point of view [11][12][13][14][15][16][17][18][19][20][21]. While all these studies have been carried out on bulk single crystals or polycrystals, there is not much work on the nano crystalline form.…”

Ferroelectricity of structural origin in the spin-chain compounds Ca3Co2−xMnxO6

“…14(a). The sud- den change at 90 K should be related to the anomaly observed in the extended x-ray absorption 30 and Mössbauer measurements. 31 However, the origin of this anomaly is still unclear.…”

“…The above XRD results indicate that the structural anomaly at 90 K is actually a huge negative expansion effect, which is similar to the case of x = 0 reported in some earlier work. 30 It seems that at T ≤ 90 K, there is overall elongation of Co-O bonds, which can be attributed to the Co 3d-O 2p hybridization and the holes in the O 2p bands. 30 We suggest that this structure anomaly does not destroy the spatial inversion symmetry and the threefold rotational symmetry still keeps.…”

“…30 It seems that at T ≤ 90 K, there is overall elongation of Co-O bonds, which can be attributed to the Co 3d-O 2p hybridization and the holes in the O 2p bands. 30 We suggest that this structure anomaly does not destroy the spatial inversion symmetry and the threefold rotational symmetry still keeps. As a result, there is probably no electric polarization below 90 K. For the x = 0.72 sample, the three Raman modes disappear and two stronger A 1g modes are detected.…”