Search

Recently, Machine Learning (ML) methods are built-in as an important component in many smart agriculture platforms. In this paper, we explore the new combination of advanced ML methods for creating a smart agriculture platform where farmers could reach out for assistance from the public, or a closed circle of experts. Specifically, we focus on an easy way to assist the farmers in understanding plant diseases where the farmers can get help to solve the issues from the members of the community. The proposed system utilizes deep learning techniques for identifying the disease of the plant from the affected image, which acts as an initial identifier. Further, Natural Language Processing techniques are employed for ranking the solutions posted by the user community. In this paper, a message channel is built on top of Twitter, a popular social media platform to establish proper communication among farmers. Since the effect of the solutions can differ based on various other parameters, we extend the use of the concept drift approach and come up with a good solution and propose it to the farmer. We tested the proposed framework on the benchmark dataset, and it produces accurate and reliable results.

The ground state of a one-dimensional spin-1/2 uniform antiferromagnetic Heisenberg chain (AfHc) is a Tomonaga-Luttinger liquid which is quantum-critical with respect to applied magnetic fields upto a saturation field Hs beyond which it transforms to a fully polarised state. Wilson ratio has been predicted to be a good indicator for demarcating these phases [Phys. Rev. B 96, 220401 (2017)]. From detailed temperature and magnetic field dependent magnetisation, magnetic susceptibility and specific heat measurements in a metalorganic complex and comparisons with field theory and quantum transfer matrix method calculations, the complex was found to be a very good realisation of a spin-1/2 AfHc. Wilson ratio obtained from experimentally obtained magnetic susceptibility and magnetic contribution of specific heat values was used to map the magnetic phase diagram of the uniform spin-1/2 AfHc over large regions of phase space demarcating Tomonaga-Luttinger liquid, saturation field quantum critical, and fully polarised states. Luttinger parameter and spinon velocity were found to match very well with the values predicted from conformal field theory., Comment: Accepted for publication in PNAS Nexus

Here, we study YbI$_3$, a quasi-2D layered material with Yb atoms arranged on an ideal honeycomb network of edge-sharing YbI$_6$ octahedra, analogous to the low-temperature phase of $\alpha-$RuCl$_3$. High quality single crystals of YbI$_3$ are grown from Yb and I as starting precursors, using the vapor transport technique. The grown crystals are characterized by single crystal x-ray diffraction, Raman spectroscopy, magnetization, and heat capacity probes. The crystal-field split ground state of Yb$^{3+}$ in \Yb~ is a well-isolated Kramers doublet with an effective moment $\rm J_{eff} = 1/2$. Upon cooling, the low-temperature heat capacity of \Yb~ reveals a broad peak at $\rm T_1 = 0.95$~K due to short-range ordering of the Yb moments, followed by a sharp peak at $\rm T_2 = T_N = 0.6$~K due to long-range ordering. The magnetic behavior is found to be weakly anisotropic with $\chi^\parallel > \chi^\perp$, where $\chi^\parallel$ and $\chi^\perp$ refers to the in-plane ($H \parallel ab$) and out-of-plane ($H \perp ab$) susceptibilities. The 2~K isothermal magnetization saturates at $\rm \approx~1.5~\mu_B/Yb^{3+}$ (in-plane) and $\rm \approx~1~\mu_B/Yb^{3+}$ (out-of-plane), suggesting the anisotropy to be easy-plane type. Low-temperature heat capacity, well below T$_N$, is found to vary as T$^\alpha$ with $\alpha~\approx~2.5$, indicating a possible unconventional magnetic ground state for YbI$_3$., Comment: 10 pages, 5 figures, Supplemental Material available on request

The association of quantum Griffiths singularity (QGS) to the magnetic-field-induced superconductor-metal transition predicts the unconventional diverging behaviour of dynamical critical exponent in low disorder crystalline two-dimensional superconductors. But whether this state exists in the superconducting systems exhibiting superconductor-insulator transition remains elusive. Here, we report the emergence of quantum Griffiths singularity in ultrathin disordered TiN thin films with more than two orders of magnitude variation in their normal state resistance. For both superconductor-metal transition and superconductor-insulator transition types, a diverging critical exponent is observed while approaching the quantum phase transition. Further, the magnetoresistance isotherms obey a direct activated scaling governed by an infinite-randomness fixed critical point. Finally, this work establishes the robustness of the QGS phenomenon towards a wide range of temperature and also towards a wide range of disorder strength as correlated with the normal state resistance., Comment: Accepted for publication in Communications Physics

Two triangular lattice antiferromagnets Sr$_3$Co(Nb,Ta)$_2$O$_9$ with an effective $j_{\rm eff}=1/2$ of Co$^{2+}$ are synthesized and their magnetic properties are investigated via magnetization and heat capacity measurements. The leading in-plane antiferromagnetic exchange coupling is estimated to be $J/k_{\rm B} \simeq 4.7$ K and 5.8 K, respectively. Both the compounds feature two-step magnetic transitions at low temperatures [($T_{\rm N1} \simeq 1.47$ K and $T_{\rm N2} \simeq 1.22$ K) and ($T_{\rm N1} \simeq 0.88$ K and $T_{\rm N2} \simeq 0.67$ K), respectively], driven by weak easy-axis anisotropy. Under magnetic field Sr$_3$CoNb$_2$O$_9$ evinces a plateau at $1/3$ magnetization. Interestingly, the high field magnetization of Sr$_3$CoTa$_2$O$_9$ reveals an exotic regime (between $H_{\rm S1}$ and $H_{\rm S2}$), below the fully polarized state in which the heat capacity at low temperatures is governed by a power law ($C_{\rm p} \propto T^{\alpha}$) with a reduced exponent $\alpha \simeq 2$. These results demonstrate an unusual field induced state with gapless excitations in the strongly frustrated magnet Sr$_3$CoTa$_2$O$_9$. The complete $T-H$ phase diagram is discussed for both the compounds., Comment: 12 pages, 7 figures, 2 tables

Here, we demonstrate an interplay between superconducting fluctuations and electron-electron interaction (EEI) by low temperature magnetotransport measurements for a set of 2D disordered TiN thin films. While cooling down the sample, a characteristic temperature T* is obtained from the R(T) at which superconducting fluctuations start to appear. The upturn in R(T) above T* corresponds to weak localization (WL) and/or EEI. By the temperature and field dependences of the observed resistance, we show that the upturn in R(T) originates mainly from EEI with a negligible contribution from WL. Further, we have used the modified Larkins electron-electron attraction strength beta(T/Tc), containing a field induced pair breaking parameter, in the Maki-Thompson (MT) superconducting fluctuation term. Here, the temperature dependence of the beta(T/Tc) obtained from the magnetoresistance analysis shows a diverging behavior close to Tc and it remains almost constant at higher temperature within the limit of ln(T/Tc) < 1. Interestingly, the variation of beta(T/Tc) on the reduced temperature (T/Tc) offers a common trend which has been closely followed by all the concerned samples presented in this study. Finally, the temperature dependence of inverse phase scattering time , as obtained from the magnetoresistance analysis, clearly shows two different regimes; the first one close to Tc follows the Ginzburg-Landau relaxation rate , whereas, the second one at high temperature varies almost linearly with temperature indicating the dominance of inelastic electron-electron scattering for the dephasing mechanism. These two regimes are followed in a generic way by all the samples in spite of being grown under different growth conditions., Comment: 7 Figures and 7 Figures in Supplemental Material; Accepted for publication Phys. Rev. B