Journal Article

IMPULSE-2026-00051

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Spin dynamics of germanium diluted ferrimagnetic spinel MnCo$_{2}$O$_{4}$

Singha, A. D. (Corresponding author) ; Pramanik, P. ; Skoulatos, M.MLZ* ; Yadav, A. ; Tiwari, P. ; Sarkar, T. ; Elkaim, E. ; Fertey, P. ; Thota, S.

2026
North-Holland Publ. Co. Amsterdam

Please use a persistent id in citations: doi:10.1016/j.jmmm.2025.173717

Abstract: We report a detailed structure and spin dynamics in two different insulating polycrystalline spinels of varying Ge and Fe contents in cubic MnCo2O4 (MCO). The stoichiometry of the investigated system being (Ge0.1Mn0.9)(Fe0.2Co1.8)O4 [G1F2] and (Ge0.2Mn0.8)(Fe0.4Co1.6)O4 [G2F4]. Both systems exhibit robust ferrimagnetic (FiM) characteristics with enhanced Curie temperature as high as TC ∼ 240 K in comparison to the pristine MCO (TC ∼ 180 K). The FiM ordering is predominantly due to the different temperature dependence of the cationic moments resulting in the effective magnetic moment = 7.36 μB/f.u. (7.1 μB/f.u. for G2F4) for G1F2. However, just below the TC both of these mixed spinels show frequency dispersion in ac-susceptibility that demonstrates the re-entrant spin-glass signatures with the freezing temperature TSG = 206 K (234.8 for G2F4) for G1F2 below TC. Formation of tiny magnetic clusters of size D ∼ 10–12 nm were probed by means of modified Langevin's expression involving M-H isotherms. Using the Néel's two-sublattice model we have extracted the strength of exchange interactions: JAA/kB ∼ −19.12 K (−25.05 K), JBB/kB ∼ 2.79 K (10.512 K), and JAB/kB ∼ 4.4 K (5.76 K) for both the systems G1F2 (G2F4). Within a certain temperature window (TH1) both compounds exhibit unusual hysteresis behaviour as the magneto crystalline anisotropy field (HK) exceeds to the coercivity (HC) for T < TH1 and becomes negligible beyond TH1.

Keyword(s): Magnetic Materials (1st) ; Condensed Matter Physics (2nd) ; Magnetism (2nd)

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Contributing Institute(s):

1. PHYSICSLAB (PHYSICSLAB)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2026

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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