Griffiths-like phase of magnetocaloricR5(SixGe1−x)

Abstract

We report on the discovery of Griffiths-like phase in several compounds of the R 5 ͑Si x Ge 1−x ͒ 4 ͑R = Gd, Tb, Dy, and Ho͒ system, through the existence of an anomalous behavior on the reciprocal magnetic susceptibility ͑ −1 ͒. We found that this anomaly is restricted to the samples which present the Gd 5 Si 2 Ge 2 -type ͑monoclinic͒ or the Sm 5 Ge 4 -type ͕orthorhombic-II ͓O͑II͔͖͒ structural phases at room temperature. This peculiar effect originates from local disorder within the crystallographic structure, stabilized and enhanced by the competing intralayer and interlayer magnetic interactions. From this strong competition, a ratio of ϳ0.5 between Néel and the Griffiths-like temperatures is always found in the O͑II͒ structure. In addition, a universal ͑x , T͒ phase diagram is proposed with an interpretation based on percolative processes.

Dynamic off-centering of Cr3+ions and short-range magneto-electric clusters in CdCr2S4Oliveira1, Pereira2, Lopes3 et al. 2012Phys. Rev. BSelf Cite271170View full textAdd to dashboardCite

“…Note that these abnormal reciprocal susceptibility features have also been observed in other compounds that present strong interplay between the lattice and spin degrees of freedom (R 5 [Si,Ge] 4 and La[Sr,Ca]MO); 19,[31][32][33] thus, a similar analysis may explain these observations.…”

Phase Competitions behind the Giant Magnetic Entropy Variation: Gd5Si2Ge2 and Tb5Si2Ge2 Case Studies

“…Such phenomenon was firstly reported in the Tb 5 Si 2 Ge 2 compound, when it was associated with the experimentally observed deviation from the expected linearity (from Curie-Weiss law) of the 1   (T) curve in the paramagnetic region, T > T C [33]. Later, different works, reported by Ouyang, Tian, Pereira and co-workers identified the Griffiths-like phase in other compounds of the R 5 T 4 family [23,[48][49][50]. All these compounds presented anomalies featuring their reciprocal susceptibility curve: a "stair-like" behavior occurring in an intermediate temperature region, T C < T < T G .…”

“…In the past few years several R 5 T 4 compounds (R = rare earth: Gd, Tb, Dy, and Ho; T = group 14 elements) have shown a Griffiths-like behavior [33,[48][49][50]. Such phenomenon was firstly reported in the Tb 5 Si 2 Ge 2 compound, when it was associated with the experimentally observed deviation from the expected linearity (from Curie-Weiss law) of the 1   (T) curve in the paramagnetic region, T > T C [33].…”

“…All these compounds presented anomalies featuring their reciprocal susceptibility curve: a "stair-like" behavior occurring in an intermediate temperature region, T C < T < T G . Later on, our group has completed the phase diagrams of the R 5 (Si x Ge 1-x ) (R = Gd, Tb, Dy and Ho) compounds with their corresponding Griffiths-like phase [50]. It was observed that despite the different main temperatures along their composition for each R compound (T G , T C and T N ), the phase diagrams were very similar in shape and two main conclusions could immediately be drawn: (1) the Griffiths singularity behavior appears only in the M and O(II) phases for compositions below a characteristic Si concentration that was defined as x p and (2) the O(II) structure is stabilized when the ratio…”

Spontaneous magnetization aboveTCin polycrystallineLa0.7Ca0.3MnO3Turcaud1, Pereira2, Sandeman3 et al. 2014Phys. Rev. BSelf Cite394191View full textAdd to dashboardCite

“…This is the feature that is commonly referred to as the signature for "Griffiths-like" phase behavior [17,20,21].…”