Reentrant magnetism at the borderline between long-range antiferromagnetic order and spin-glass behavior in the B -site disordered perovskite system Ca2−xS

Abstract

We report on the coexistence of magnetic order and disorder in the atomically disordered double perovskites Ca2FeRuO6 and CaSrFeRuO6. Powder x-ray and neutron diffraction were used to investigate the crystal structure and magnetic ordering of these oxides. Both compounds are described by the orthorhombic space group Pbnm down to 3 K, where the B-site is found to be statistically occupied by Fe 3+ and Ru 5+ ions. The compound Ca2FeRuO6 shows a G-type antiferromagnetic ordering at TN ≈ 220 K, where the moments are aligned parallel to the c axis.The exchange of Ca by Sr suppresses long-range ordering in this system with the consequence that CaSrFeRuO6 shows a diffuse scattering pattern, indicating only the presence of a short-range order of the magnetic moments. Mössbauer measurements additionally reveal the coexistence of long-range ordered and paramagnetic phase in Ca2FeRuO6, and spin-glass behavior in CaSrFeRuO6. The random occupancy of iron and ruthenium atoms at the B-site gives rise to locally varying competing magnetic exchange interactions which favors the emergence of reentrant magnetism with a spin-glass-like transition at Tf ≈ 87 K for Ca2FeRuO6 and a spin-glass transition at ~65 K for CaSrFeRuO6, as evidenced by frequency dependent ac susceptibility measurements. Our results are an interesting example for crossing the borderline between antiferromagnetism and spin-glass behavior in a 3d-4d hybrid perovskite system by rather modifying structural details described by the tolerance factor of the perovskite structure than by changing the concentration of magnetic ions.

Evidence for cluster spin glass phase with precursor short-range antiferromagnetic correlations in the B -site disordered Ca(Fe1/2Kumar1, Senyshyn2, Pandey3 2019Phys. Rev. B387210View full textAdd to dashboardCite

“…In the second model, which is supported by microscopic measurements (neutron and Mössbauer techniques), on the other hand, the SG phase is argued to result from the LRO AFM sublattice system itself due to freezing of the transverse component of the spin in a glassy manner [31]. It is worth mentioning here that the study of SG transition in ordered [29,[47][48][49] and disordered [29,[50][51][52] double perovskites continues to attract enormous attention in the current literature.…”

“…Within the broad family of such site-and charge-disordered/ordered compounds, complex perovskites with the formula A(B 1/2 B 1/2 )O 3 , where B : B are in 1 : 1 ratio, commonly known as double perovskites, have received immense attention from the point of view of the colossal magnetoresistance [11][12][13], half metallicity [14][15][16], metal to insulator transition [17][18][19], superconductivity [20,21], etc. ), normal ferroelectricity [9] and relaxor ferroelectricity [4][5][6][22][23][24], long-range magnetic ordering [25][26][27][28][29][30][31], and multiferroicity [32][33][34][35]. Multiferroicity in the double perovskites of the type A(B 1/2 B 1/2 )O 3 with A = Pb, Ba, Sr, Ca can be * dp.mst1979@gmail.com easily introduced by choosing one of the B-site cations with partially filled d orbitals (d n ) imparting magnetic properties (e.g., Cr, Mn, Fe, Co, Ni, Ru, Re, Os, Ir) and the other with unfilled d orbitals (d 0 ) (e.g., Nb, Sb, Ta, W, Mo) required for inducing ferroelectric distortion [36], as was first demonstrated by Russian scientists who synthesized these complex multiferroic perovskites nearly six decades back [37][38][39].…”

Investigation of New B-Site-Disordered Perovskite Oxide CaLaScRuO6+δ: An Efficient Oxygen Bifunctional Electrocatalyst in a Highly Alkaline Medium

“…As per previously reported works, carbon materials with transition metal oxides and heteroatom doping and transition metal oxides/hydroxides − have been used for OER/ORR in the alkaline electrolyte as a bifunctional material, but stability is an issue. Alternatively, transition metal carbides, selenides, nitrides, chalcogenides, and a class of metal oxides including oxygen-rich/deficient perovskites, brownmillerites, spinels, pyrochlores, etc., are considered as efficient photo/electrocatalysts for OER and ORR activities. − Among many, perovskites ( AB O 3 ) and double perovskite (DP) metal compounds ( AA ′ BB ′O 6 ) (where A and A ′ are lanthanides or alkaline earth metals and B and B′ are transition elements) and related oxides possess a number of advantages, including robust structure with tunable physicochemical properties, − high stability under highly alkaline conditions, and facile synthesis procedure. Some strategies like doping of elements with varying valence state, electronegativity, addition with carbon materials, surface treatment, and substitution with other transition metals into the A- and B- site directly influence the resultant properties of these catalysts and have been adopted for achieving the best ORR/OER activity. , Some 3d transition metal-based perovskites like LaVO 3 , LaMnO 3 , SrFeO 3 , La M O 3 ( M = Mn, Fe, and Co) perovskite nanoparticles have been studied for OER/ORR. , Mixed metal oxides have produced great interest due to good catalytic performance arising from the synergistic effect among the metal ions.…”

Integrated experimental and theoretical studies on structural and magnetic properties of thin films of double perovskite ruthenates: Ba2DyRuO6 & Sr2DyRuO6

“…Among these rare-earth-based compounds, we are particularly interested in specific double perovskites (DPs), having general formula A 2 BRuO 6 (where A = Sr, Ba, Ca, and B = a rare earth ion) due to their fascinating properties such as metallic/half-metallic nature, multiferroics, colossal magnetoresistance (CMR), canted anti-ferromagnetism, 13–16 etc. , especially at low temperatures.…”