Anomalous magnetic properties ofSr2YRuO6

Abstract

Anomalous magnetic properties of the double perovskite ruthenate compound Sr 2 YRuO 6 are reported here. Magnetization measurements as a function of temperature in low magnetic fields show clear evidence for two components of magnetic order ͑T M1 ϳ 32 K and T M2 ϳ 27 K͒ aligned opposite to each other with respect to the magnetic-field direction even though only Ru 5+ moments can order magnetically in this compound. The second component of the magnetic order at T M2 ϳ 27 K results only in a magnetization reversal, and not in the negative magnetization when the magnetization is measured in the field-cooled ͑FC͒ mode. Isothermal magnetization ͑M-H͒ measurements show hysteresis with maximum coercivity ͑H c ͒ and remnant magnetization ͑M r ͒ at T ϳ 27 K, corroborating the presence of the two oppositely aligned magnetic moments, each with a ferromagnetic component. The two components of magnetic ordering are further confirmed by the double peak structure in the heat-capacity measurements. These anomalous properties have significance to some of the earlier results obtained for the Cu-substituted superconducting Sr 2 YRu 1−x Cu x O 6 compounds.

Exchange bias-like properties in Sr2YRuO6

“…The values of E H and coercivity ( c H ) as a function of temperature are shown in figure 2. H E decreases as temperature is increased and vanishes above T* ~ 26 K. On the other hand, H c increases with temperature upto T* ~ 26 K and thereafter decreases and disappears above N T~ 32 K. We have attributed [11] this behaviour of coercivity to a spin-reversal in this system. The disappearance of EB at T* ~ 26 K then implies that the mechanism causing the spin reversal triggers the exchange bias-like mechanism also.…”

“…Sr 2 YRuO 6 shows magnetic ordering [11] at N T~ 32 K (see the inset in figure 1). Neutron diffraction measurements have revealed the nature of magnetic ordering to be antiferromagnetic [12].…”

“…T clearly indicates the presence of a ferromagnetic component among the ordered Ru moments [11]. We have measured the ZFC/FC magnetization isotherms at 25 K. For the ZFC/FC process, the sample was cooled in zero applied magnetic field/10 kOe from a temperature well above the magnetic ordering to 25 K. Then, the hysteresis loops were measured between ± 40 kOe.…”

Temperature and doping dependence of normal state spectral properties in a two-orbital model for ferropnictides

“…The low temperature results agree also with LDA+DFMT calculations in SmO 1−x F x FeAs, 11 LDA+DFT calculations in LaFeAsO 1−x F x , 10 BaFe 2 As 2 13 and LiFeAs. 13 Regarding the evolution with temperature shown in Fig. 4, our calculations predict that this intense sharp peak near the Fermi level should be clearly observed for temperatures T < 40K.…”

“…8,9 For LaOFeAs, calculations were carried out almost simultaneously in a number of works. [10][11][12][13][14] The Fermi surface topology and band structure are rather similar for the 11 (e.g. FeSe), 111 ( e.g.…”