Existence of Griffiths phase and unusual spin dynamics in double perovskite Tb2CoMnO6

AbstractComplex iridium oxides have attracted recently a substantial interdisciplinary attention due to an intimate entanglement of spin and orbital degrees of freedom which may give rise to a novel spin–orbital Mott insulating behavior and exotic quantum spin liquid phases. Electron spin resonance (ESR) spectroscopy is known to be an instructive tool for studying the spin–orbital coupling (SOC) effects as it can directly access the relevant parameters sensitive to SOC, such as the g factor tensor, magnetic anisotropy gaps and spin dynamics. In this article, a systematic study at the Leibniz IFW Dresden of the static and dynamic properties of selected Ir-based materials with multi-frequency high-field ESR spectroscopy will be reviewed. Specifically, evidence for a surprisingly isotropic antiferromagnetic spin dynamics and the inversion of the orbital states in the prototypical spin–orbital Mott insulator $$\text {Sr}_2\text {IrO}_4$$ Sr 2 IrO 4 , observation of the collective resonance modes in the family of double perovskites $$\text {La}_2$$ La 2 B$$\text {IrO}_6$$ IrO 6 (B = Cu, Co) and the origin of the unexpected magnetism in the double perovskite $$\text {Ba}_2\text {YIrO}_6$$ Ba 2 YIrO 6 will be highlighted.

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Development of short and long-range magnetic order in the double perovskite based frustrated triangular lattice antiferromagnet Ba$$_{2}$$MnTeO$$_{6}$$

Scientific Reports ◽

10.1038/s41598-021-84876-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

J. Khatua ◽

T. Arh ◽

Shashi B. Mishra ◽

H. Luetkens ◽

A. Zorko ◽

...

Keyword(s):

Triangular Lattice ◽

Degrees Of Freedom ◽

Spin Dynamics ◽

Muon Spin ◽

Magnetic Ordering ◽

Double Exchange ◽

Double Perovskite ◽

Magnetic Interactions ◽

Spin Frustration ◽

Ordered State

AbstractFrustrated magnets based on oxide double perovskites offer a viable ground wherein competing magnetic interactions, macroscopic ground state degeneracy and complex interplay between emergent degrees of freedom can lead to correlated quantum phenomena with exotic excitations highly relevant for potential technological applications. By local-probe muon spin relaxation ($$\mu$$ μ SR) and complementary thermodynamic measurements accompanied by first-principles calculations, we here demonstrate novel electronic structure and magnetic phases of Ba$$_{2}$$ 2 MnTeO$$_{6}$$ 6 , where Mn$$^{2+}$$ 2 + ions with S = 5/2 spins constitute a perfect triangular lattice. Magnetization results evidence the presence of strong antiferromagnetic interactions between Mn$$^{2+}$$ 2 + spins and a phase transition at $$T_{N}$$ T N = 20 K. Below $$T_{N}$$ T N , the specific heat data show antiferromagnetic magnon excitations with a gap of 1.4 K, which is due to magnetic anisotropy. $$\mu$$ μ SR reveals the presence of static internal fields in the ordered state and short-range spin correlations high above $$T_{N}$$ T N . It further unveils critical slowing-down of spin dynamics at $$T_{N}$$ T N and the persistence of spin dynamics even in the magnetically ordered state. Theoretical studies infer that Heisenberg interactions govern the inter- and intra-layer spin-frustration in this compound. Our results establish that the combined effect of a weak third-nearest-neighbour ferromagnetic inter-layer interaction (owing to double-exchange) and intra-layer interactions stabilizes a three-dimensional magnetic ordering in this frustrated magnet.

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