Large Magnetoresistance and Jahn Teller effect in Sr${}_2$FeCoO${}_6$

Abstract

Neutron diffraction measurement on the spin glass double perovskite Sr${}_2$FeCoO${}_6$ reveals site disorder as well as Co${}^{3+}$ intermediate spin state. In addition, multiple valence states of Fe and Co are confirmed through Mössbauer and X-ray photoelectron spectroscopy. The structural disorder and multiple valence lead to competing ferromagnetic and antiferromagnetic interactions and subsequently to a spin glass state, which is reflected in the form of an additional $T$-linear contribution at low temperatures in specific heat. A clear evidence of Jahn-Teller distortion at the Co${}^{3+}$-O${}_6$ complex is observed and incorporating the physics of Jahn-Teller effect, the presence of localized magnetic moment is shown. A large, negative and anomalous magnetoresistance of $\approx$ 63% at 14K in 12T applied field is observed for Sr${}_2$FeCoO${}_6$. The observed magnetoresistance could be explained by applying a semi-empirical fit consisting of a negative and a positive contribution and show that the negative magnetoresistance is due to spin scattering of carriers by localized magnetic moments in the spin glass phase.

References in corpus (2)

• Excess specific heat and evidence of zero point entropy in magnetic glassy state of half-doped manganites
• Enhancement of giant magnetoresistance effect in the Ruddlesden-Popper phase Sr3Fe2-xCoxO7-d: Predominant role of oxygen nonstoichiometry and magnetic phase separation

Cited by in corpus (4)

• Unraveling the magnetic interactions and spin state in insulating Sr${}_{2-x}$La${}_x$CoNbO${}_6$
• Contrasting the magnetism in La${}_{2-x}$Sr${}_x$FeCoO${}_6$ ($x$ = 0, 1, 2) double perovskites: the role of electronic and cationic disorder
• Hyperfine interaction and electronic spin fluctuation study on Sr${}_{2-x}$La${}_x$FeCoO${}_6$ (x = 0, 1, 2) by high-resolution back-scattering neutron spectroscopy
• A possibility of high spin hole states in doped CoO${}_2$ layered systems