Magnetic anomalies in the spin-chain compoundSr3CuRhO6: Griffiths-phase-like behavior of magnetic susceptibility

Abstract

We report the results of ac and dc magnetic susceptibility (χ), heat-capacity (C), isothermal magnetization and isothermal remanent magnetization measurements on the compound, Sr 3 CuRhO 6 , crystallizing in a K 4 CdCl 6 -derived monoclinic structure. The magnetization data reveal distinct magnetic anomalies near 6 and 12 K with decreasing temperature (T). While the transition below (T o =) 6K appears to be of a spin-glass-type as inferred from all the data, the one at 12 K is not typical of bulk ferromagnetism in contrast to an earlier proposal. In the range 6 to 12 K, the dc χ obeys the form, χ -1 α (T-T o ) 1-λ (0<λ<1) for very low dc fields and the values of χ decrease gradually with the application of higher magnetic fields, mimicking the behavior Griffiths-phases. IntroductionThe spin-chain compounds of the type, (Sr,Ca) 3 MXO 6 (M, X= transition metal ions), with M-X magnetic chains running along c-axis separated by Sr (Ca) ions, derived from K 4 CdCl 6 -type rhombohedral structure (space group c R3 ) have attracted considerable interest in recent years [1][2][3]. MO 6 (distorted) trigonal prism and XO 6 (distorted) octahedra share a face. In general, intrachain interaction is ferromagnetic, whereas interchain interaction is antiferromagnetic. The magnetic chains are placed in a triangular fashion in the basal plane and hence often geometrically frustrated magnetism, particularly with unusual features, are observed among this class compounds. The Cu containing compounds (at the M site) are especially interesting, as these undergo monoclinic distortion (space group C2/c) due to Jahn-Teller effect, as a result of which Cu ions are displaced alternately to the right and to the left with respect to the X-ion chain in a zig-zag fashion, thereby tending towards square-planar coordination (see Ref. 1 for details). In this article, we present the results of our investigations on Sr 3 CuRhO 6 , particularly considering that a previous preliminary report based on dc magnetization studies [1] claimed that this compound is ferromagnetic below (T C = ) 12 K.

Finite-size effect on evolution of Griffiths phase in manganite nanoparticles

“…The very negligible λ P M in PM regime (above T G ) implies that obtained T R c are authentic. The obtained λ GP in GP regime are quite comparable with other TMOs [14,[16][17][18][24][25][26]. We observe that λ GP increases and T R c decreases with reducing the particle size.…”

Insight into the magnetism of a distorted Kagome lattice, Dy 3 Ru 4 Al 12 , based on polycrystalline studies

“…The appearance of such a collective phase before long range ordering could be a manifestation of geometrical frustration, as proposed in Ref. 14. The AC χ features are rather weak around this characteristic temperature, but the ν-dependence is clearly discernable; since MIRM decay is not observed, we conclude that this ν-dependence does not arise from spin-glass dynamics, but may be due to domain dynamics of ferromagnetic clusters, as reported for Sr3CuRhO6 [15]. Such a magnetic precursor effect clearly manifests in a large linear term in heat-capacity.…”

“…1. In order to get a better picture, we have measured MR as a function of H at selected temperatures (2,5,8,15 and 35 K; see figure 9). The shape of the MR curve is qualitatively different from that reported for single crystals [1] at 2 and 5 K. That is, in the virgin curve of MR(H), there is an upturn at the metamagnetic transition field around 10 kOe and then a peak appears; the value subsequently undergoes a steep fall, exhibits a shoulder around 40 kOe and then changes sign (to negative) just beyond 50 kOe.…”

Exotic magnetic behaviour and evidence of cluster glass and Griffiths like phase in Heusler alloys Fe2-xMnxCrAl (0 ≤ x ≤ 1)

“…Under the application of the magnetic field, it is noticed that the downturn softens (shown in figure 11 (k) and (l) corresponding to Fe 2 CrAl and FeMnCrAl, respectively). Similar suppression of the downturn has also been reported in the GP regime of other magnetic systems [53][54][55]. In general, Griffith's singularity can be characterized using the exponent (λ) which can be obtained from the expression…”