Heat Capacity, Magnetic And Lattice Dynamic Properties Of Pseudo-two Dimensional: M2Fe2O(AsO4)2 [M=K, K0.79Cs0.21 and Rb] Compounds

Pramod Kumar1*, Rashmi Singh1, L. D. Sanjeewa2, Rachana Kumar3**

Adv. Mater. Lett., 2016, 7 (12), pp 964-970

DOI: 10.5185/amlett.2016.6450

Publication Date (Web): Oct 12, 2016

E-mail:pkumar@iiita.ac.in; rachanak@nplindia.org

Abstract


In this paper, structural, magnetic and heat capacity of M2Fe2O(AsO4)2 compounds have been reported. Most interestingly, the magnetization at very low fields  a complete negative magnetization was observed in both field cooling and zero field cooling in K2Fe2O(AsO4)2 and Rb2Fe2O(AsO4)2 compounds whereas field cooled is positive in KCsFe2O(AsO4)2. A possible mechanism for the observed peculiar magnetic behavior is discussed, related to the competition of the single-ion magnetic anisotropy and the antisymmetric magnetization behavior in two crystallographically different FeO6 centers. We estimated the gap (D)  opening at low temperature K2Fe2O (AsO4)2 KCs2Fe2O (AsO4)2 and Rb2Fe2O (AsO4)2, are 23.6 K, 23.9 K and 25 K respectively from heat capacity. Magnetic part of heat capacity at low temperatures follows the T3 dependence, indicates that the low temperature magnetic state in all these compounds are antiferromagnetic.

Keywords

Magnetization, heat capacity, magnetic frustrations: antiferromagnetic.

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