Non-Griffiths-like cluster formation in the double-perovskite Gd2CoMnO6 : Evidence from critical behavior

Magnetoelastic Coupling and Cryogenic Magnetocaloric Effect in Two-Site Disordered GdSrCoFeO6 Double Perovskite

“…However, the C p / T vs T curves, shown in the top-left inset, reveal a broad downward hump at ∼18 K and another less wide upward at ∼5 K. The peak at ∼5 K (curve in 9 T) corresponds to the onset of AFM ordering of Gd 3+ magnetic moments, whereas at ∼18 K is attributed to the Schottky contribution that arises from crystal field transitions related mostly to the f -electrons of Gd 3+ . Similar behavior is commonly seen in other double perovskite compounds. − These anomalies are characteristic of disordered systems for which the competing magnetic interactions lead to short-range correlations . The lower right inset in Figure c shows the θ D as a function of temperature.…”

“…Second, separated by the critical isotherm in Figure b of 65 K, M S and χ 0 –1 have been extracted and plotted vs temperature (see Figure c) and analyzed with eqs and , (gray dashed lines in Figure c) yielding β = 1.468 with T C = 65.13 K and γ = 1.457 with T C = 65.21 K. These values are very consistent with that achieved from the MAP plot. Using the Widom scaling relation δ = 1 + γ/β, we obtain δ = 1.993. As shown in the inset of Figure c, the ln M vs ln H 1/δ curve for isotherm at T C = 65 K obeys the linearity predicted by eq .…”

“…To gain further insight into the FM/FiM to PM transition, we investigated in detail the critical behavior characterized by the critical exponents in GdSrCoFeO 6 by comparing several analysis methods. In the vicinity of SOPT, the diverging correlation length leads to the universal scaling laws for spontaneous magnetization ( M S ), initial susceptibility (χ 0 ), and magnetization at T C via a set of critical exponents β, γ, and δ . Mathematically, the exponents from magnetization can be described as: , M normalS ( 0 , ϵ ) ∼ false( prefix− ϵ false) β , ϵ < 0 , T < T normalC χ 0 − 1 ( 0 , ϵ ) ∼ false( ϵ false) γ , ϵ > 0 , T > T normalC M ( H , 0 ) ∼ false( H false) 1 / δ , ϵ = 0 , T = T normalC where ϵ = ( T – T C )/ T C is the reduced temperature.…”

“…In order to certify the reliability of the obtained critical exponents, the scaling hypothesis was analyzed by the magnetic equation of state in the asymptotic critical region, defined as: M ( H , ϵ ) = false| ϵ false| β f ± ( H | ϵ | β δ ) where f ± are regular functions with f + for temperatures above T C and f – for temperatures below T C . Using the β, δ, and T C values obtained from MAP, we have represented the M |ϵ| –β vs H |ϵ| –(β + δ) plot and the same plot in the log–log scale, as shown in Figure .…”

“…89−91 These anomalies are characteristic of disordered systems for which the competing magnetic interactions lead to short-range correlations. 20 The lower right inset in Figure 5c shows the θ D as a function of temperature. As can be seen, the curve follows linearity up to T ∼ 18 K, yielding θ D ∼ 270 and 220 K for 0 and 9 T, respectively.…”