Showing papers by "S. M. Yusuf published in 2021"
TL;DR: In this paper, a series of scandium-based NASICON compounds, namely Na3+xSc2Si0·4P2·6O12 (x = 0.0, 0.2, 0., 0.4, and 0.8) have been prepared by the ceramic route.
8 citations
TL;DR: In this paper, the authors present a quasi-one-dimensional spin system with Gapless excitations and show that the magnetic heat capacity follows nearly a linear behavior at low temperatures.
Abstract: Competing magnetic interactions in low-dimensional quantum magnets can lead to the exotic ground state with fractionalized excitations. Herein, we present our results on an $S=\frac{5}{2}$ quasi-one-dimensional spin system ${\mathrm{Bi}}_{3}{\mathrm{FeMo}}_{2}{\mathrm{O}}_{12}$. The structure of ${\mathrm{Bi}}_{3}{\mathrm{FeMo}}_{2}{\mathrm{O}}_{12}$ consists of very well separated, infinite zigzag $S=\frac{5}{2}$ spin chains. The observation of a broad maximum around 10 K in the magnetic susceptibility $\ensuremath{\chi}(T)$ suggests the presence of short-range spin correlations. $\ensuremath{\chi}(T)$ data do not fit the $S=\frac{5}{2}$ uniform spin chain model due to the presence of second-nearest-neighbor coupling (${J}_{2}$) along with the first-nearest-neighbor coupling (${J}_{1}$) of the zigzag chain. The electronic structure calculations infer that the value of ${J}_{1}$ is comparable with ${J}_{2}$ (${J}_{2}/{J}_{1}\ensuremath{\approx}1.1$) with a negligible interchain interaction (${J}^{\ensuremath{'}}/J\ensuremath{\approx}0.01$) implying that ${\mathrm{Bi}}_{3}{\mathrm{FeMo}}_{2}{\mathrm{O}}_{12}$ is a highly frustrated triangular chain system. The absence of magnetic long-range ordering down to 0.2 K is seen in the heat-capacity data, despite a relatively large antiferromagnetic Curie-Weiss temperature ${\ensuremath{\theta}}_{CW}\ensuremath{\approx}--\phantom{\rule{0.16em}{0ex}}40$ K. The magnetic heat capacity follows nearly a linear behavior at low temperatures indicating that the $S=\frac{5}{2}$ anisotropic triangular chain exhibits the gapless excitations.
4 citations
TL;DR: In this paper, the thermal response of the gapped broad band over a high temperature range possibly marks a spin liquid phase in a geometrically frustrated layered kagome system.
Abstract: Experimental detection of spin dynamics of the quantum spin liquid phase, which occurs when the quantum fluctuations lead to fractionalized spin states, remains a challenge. In this paper, we illustrate spin-liquid signatures in the geometrically frustrated layered kagome system $\mathrm{YBa}{\mathrm{Co}}_{4\ensuremath{-}x}{\mathrm{Fe}}_{x}{\mathrm{O}}_{7+\ensuremath{\delta}}$ ($x=0$ and $x=0.6$) over a wide temperature range using micro-Raman spectroscopy. The thermal response of the gapped broad band over a high temperature range possibly marks a spin liquid phase in this system. We report the appearance of sharp spectral features in the high temperature regime with unusual thermal behavior for $\mathrm{YBa}{\mathrm{Co}}_{4\ensuremath{-}x}{\mathrm{Fe}}_{x}{\mathrm{O}}_{7+\ensuremath{\delta}}$ ($x=0.6$). Besides, atypical oscillation of a phonon mode frequency with temperature suggests an unconventional electron-lattice coupling in the doped compound via a strong correlation between their lattice vibration and magnetic spin dynamics.
2 citations