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We present CoTe2 as a new type-II Dirac semimetal supporting Lorentz symmetry violating Dirac fermions in the vicinity of the Fermi energy. By combining first principle ab-initio calculations with experimental angle-resolved photo-emission spectroscopy results, we show the CoTe2 hosts a pair of type-II Dirac fermions around 90 meV above the Fermi energy. In addition to the bulk Dirac fermions, we find several topological band inversions in bulk CoTe2, which gives rise to a ladder of spin-polarized surface states over a wide range of energies. In contrast to the surface states which typically display Rashba-type in-plane spin splitting, we find that CoTe2 hosts novel out-of-plane spin polarization as well. Our work establishes CoTe2 as a potential candidate for the exploration of Dirac fermiology and applications in spintronic devices, infrared plasmonics, and ultrafast optoelectronics., Comment: 9 pages,7 figures, Accepted in Phys. Rev. B

Introduction:- Orofacial granulomatosis (OFG) is a disease entity with recurrent or persistent edema within the orofacial region. It frequently manifests as persistent and/or recurrent upper and/or lower labial lip and gingival enlargement. Histological features are non-necrotizing granulomas form in the affected tissues in the absence of any recognized systemic disease. The denite etiology of OFG is unidentied.1 Numerous theory have been recommended, including infection, genetic predisposition, and allergy.2-6 This report is a remarkable case ofCase report:- orofacial granulomatosis which presented as a recurrent severe generalized gingival enlargement in a eleven year-old child. There was no family history and no data of an underlying allergic or systemic cause. Oral prophylaxis showed mild alleviation of symptoms. Diagnosis ofConclusion: - orofacial granulomatosis is often difcult. OFG is cured by appropriate treatment.

Flat bands in twisted moire superlattices support a variety of topological and strongly correlated phenomena along with easily tunable electrical and optical properties. Here, we demonstrate the existence of tunable, long-lived, and flat intraband and interband terahertz plasmons in twisted double bilayer graphene. We show that the interband plasmons originate from the presence of a Van Hove singularity in the joint density of states and a finite Berry connection between the pair of bands involved. We find that the gapped interband plasmon mode has a universal dispersion, and the plasmon gap is specified by the location of the Van Hove singularity in the joint density of states. Metallic moire systems support an additional intraband plasmon mode which becomes flat in the large momentum limit because of the influence of the interband correlations. We demonstrate that the undamped and flat plasmon modes in moire systems are highly tunable and can be controlled by varying the vertical electric field and electron doping, and they persist over a wide range of twist angles., 4 figures, 9 pages

Nonreciprocal plasmonics enables one-way light propagation at the nanoscale and it is an essential building block for photonics applications. Here, we explore intrinsic nonreciprocity in bulk plasmon propagation based on underlying symmetries. We demonstrate that the interband, as well as the intraband bulk plasmon modes, follow asymmetric dispersion depending on the sign of the wavevector for systems with broken inversion and time-reversal symmetry. We show that the nonreciprocity in the interband plasmon dispersion is dictated by the quantum metric connection, which is a band geometric quantity. The intrinsic nonreciprocity in bulk intraband plasmon dispersion is dictated by the quantum metric dipole and a higher-order `Drude' weight-like term. We corroborate our findings via explicit numerical calculations for the two-dimensional Qi-Wu-Zhang model and demonstrate the existence of intrinsic nonreciprocal intraband and interband plasmon modes in moire systems such as twisted bilayer graphene., Comment: 14 pages, 6 figures

Topological aspects of electron wavefunction play a crucial role in determining the physical properties of materials. Berry curvature and Chern number are used to define the topological structure of electronic bands. While Berry curvature and its effects in materials have been studied, detecting changes in the topological invariant, Chern number, is challenging. In this regard, twisted double bilayer graphene (TDBG) has emerged as a promising platform to gain electrical control over the Berry curvature hotspots and the valley Chern numbers of its flat bands. In addition, strain induced breaking of the three-fold rotation (C3) symmetry in TDBG, leads to a non-zero first moment of Berry curvature called the Berry curvature dipole (BCD), which can be sensed using nonlinear Hall (NLH) effect. We reveal, using TDBG, that the BCD detects topological transitions in the bands and changes its sign. In TDBG, the perpendicular electric field tunes the valley Chern number and the BCD simultaneously allowing us a tunable system to probe the physics of topological transitions. Furthermore, we find hysteresis of longitudinal and NLH responses with electric field that can be attributed to switching of electric polarization in moir\'e systems. Such a hysteretic response holds promise for next-generation Berry curvature-based memory devices. Probing topological transitions, as we show, can be emulated in other 3D topological systems., Comment: 21 pages, 9 figures, and supplementary information

Nonlinear anomalous Hall effect is the Berry curvature dipole induced second-order Hall voltage or temperature difference in response to a longitudinal electric field or temperature gradient. These are the prominent Hall responses in time reversal symmetric systems. Here, we investigate the family of second-order nonlinear anomalous Hall effects, the electrical, thermoelectric and thermal nonlinear Hall effects in the moir\'e system of twisted double bilayer graphene. We demonstrate that the nonlinear anomalous Hall signals can be used to probe the topological phase-transitions in moir\'e systems, induced by a perpendicular electric field. Specifically, we show that the whole family of nonlinear anomalous Hall responses undergo a sign reversal across a topological phase-transition., Comment: 12 pages, 6 figures, Comments are welcome

Recently, there have been contrary claims of Kitaev spin-liquid behavior and ordered behavior in the honeycomb compound ${\mathrm{Ag}}_{3}\mathrm{Li}{\mathrm{Ir}}_{2}{\mathrm{O}}_{6}$ based on various experimental signatures. Our investigations on this system reveal a low-temperature ordered state with persistent dynamics down to the lowest temperatures. Magnetic order is confirmed by clear oscillations in the muon spin relaxation ($\ensuremath{\mu}\mathrm{SR}$) time spectrum below 9 K until 52 mK. Coincidentally in $^{7}\mathrm{Li}$ nuclear magnetic resonance, a wipeout of the signal is observed below $\ensuremath{\sim}10$ K, which again strongly indicates magnetic order in the low-temperature regime. This is supported by our density functional theory calculations which show an appreciable Heisenberg exchange term in the spin Hamiltonian that favors magnetic ordering. The $^{7}\mathrm{Li}$ shift and spin-lattice relaxation rate also show anomalies at $\ensuremath{\sim}50$ K. They are likely related to the onset of dynamic magnetic correlations, but their origin is not completely clear. Detailed analysis of our $\ensuremath{\mu}\mathrm{SR}$ data is consistent with a coexistence of incommensurate N\'eel and striped environments. A significant and undiminished dynamical relaxation rate ($\ensuremath{\sim}5$ MHz) as seen in $\ensuremath{\mu}\mathrm{SR}$ deep into the ordered phase indicates enhanced quantum fluctuations in the ordered state.

We report gapless quantum spin liquid behavior in the layered triangular ${\mathrm{Sr}}_{3}{\mathrm{CuSb}}_{2}{\mathrm{O}}_{9}$ system. X-ray diffraction shows superlattice reflections associated with atomic site ordering into triangular Cu planes well separated by Sb planes. Muon spin relaxation measurements show that the $S=\frac{1}{2}$ moments at the magnetically active Cu sites remain dynamic down to 65 mK in spite of a large antiferromagnetic exchange scale evidenced by a large Curie-Weiss temperature ${\ensuremath{\theta}}_{\mathrm{CW}}\ensuremath{\simeq}\ensuremath{-}143\text{ }\text{ }\mathrm{K}$ as extracted from the bulk susceptibility. Specific heat measurements also show no sign of long-range order down to 0.35 K. The magnetic specific heat (${C}_{m}$) below 5 K reveals a ${C}_{m}=\ensuremath{\gamma}T+\ensuremath{\alpha}{T}^{2}$ behavior. The significant ${T}^{2}$ contribution to the magnetic specific heat invites a phenomenology in terms of the so-called Dirac spinon excitations with a linear dispersion. From the low-$T$ specific heat data, we estimate the dominant exchange scale to be $\ensuremath{\sim}36\text{ }\text{ }\mathrm{K}$ using a Dirac spin liquid ansatz which is not far from the values inferred from microscopic density functional theory calculations ($\ensuremath{\sim}45\text{ }\text{ }\mathrm{K}$) as well as high-temperature susceptibility analysis ($\ensuremath{\sim}70\text{ }\text{ }\mathrm{K}$). The linear specific heat coefficient is about $18\text{ }\text{ }\mathrm{mJ}/\mathrm{mol}\text{ }{\mathrm{K}}^{2}$ which is somewhat larger than for typical Fermi liquids.

We report gapless quantum spin liquid behavior in the layered triangular Sr_{3}CuSb_{2}O_{9} system. X-ray diffraction shows superlattice reflections associated with atomic site ordering into triangular Cu planes well separated by Sb planes. Muon spin relaxation measurements show that the S=1/2 moments at the magnetically active Cu sites remain dynamic down to 65 mK in spite of a large antiferromagnetic exchange scale evidenced by a large Curie-Weiss temperature θ_{CW}≃-143 K as extracted from the bulk susceptibility. Specific heat measurements also show no sign of long-range order down to 0.35 K. The magnetic specific heat (C_{m}) below 5 K reveals a C_{m}=γT+αT^{2} behavior. The significant T^{2} contribution to the magnetic specific heat invites a phenomenology in terms of the so-called Dirac spinon excitations with a linear dispersion. From the low-T specific heat data, we estimate the dominant exchange scale to be ∼36 K using a Dirac spin liquid ansatz which is not far from the values inferred from microscopic density functional theory calculations (∼45 K) as well as high-temperature susceptibility analysis (∼70 K). The linear specific heat coefficient is about 18 mJ/mol K^{2} which is somewhat larger than for typical Fermi liquids.

Motivated by the recent report on the high-${T}_{c}$ ferromagnetic insulating state of a single transition metal containing a double perovskite compound, ${\mathrm{Sr}}_{3}{\mathrm{OsO}}_{6}$ [Wakabayashi et al., Nat Commun. 10, 535 (2019)], we study this curious behavior by employing first-principles calculations in conjunction with exact diagonalization of the full ${t}_{2g}$ multiplet problem of two Os sites. Our analysis highlights the fact that stabilization of ${\mathrm{Sr}}_{3}{\mathrm{OsO}}_{6}$ in the cubic phase in epitaxially grown thin film is the key to both ferromagnetic correlation and the high-temperature scale associated with it. It also provides a natural explanation for why the sister compound, ${\mathrm{Ca}}_{3}{\mathrm{OsO}}_{6}$, exhibits low-${T}_{N}$ antiferromagnetism in its monoclinic structure. Furthermore, the insulating property is found to be driven by the opening of a Mott gap in the half-filled spin-orbit coupled $j=3/2$ manifold of ${d}^{2}$ Os. We point out that ${\mathrm{Sr}}_{2}{\mathrm{CaOsO}}_{6}$, which naturally forms in the cubic phase, would be worthwhile to explore as a future candidate to exhibit a high-${T}_{c}$ ferromagnetic insulating state in bulk form.

We have studied a Fe-based di-nuclear molecular complex having the chemical formula [{Fe(bpp)(NCS)2}2([Formula: see text]'-bipy)]·2MeOH (where bpp = [Formula: see text]-bis(pyrazol-3-yl) pyridine and [Formula: see text]'-bipy = [Formula: see text]'-bipyridine, 1) using density functional theory and model Hamiltonian approach. Our study provides insight to the pressure driven spin-crossover (SCO) phenomena observed experimentally in these systems. Upon increasing the pressure, the spin state of Fe(II) cation gradually changes from a high spin state (S =2) to a low spin (LS) state (S =0) accompanied by volume contraction. The gradual increase in pressure shrinks Fe-N bond length and also causes angular deviation of the FeN6 octahedron leading to full conversion to the LS state without global structural phase transition. We have carried out exact diagonalization study of an effective single site Hamiltonian and confirmed the importance of intramolecular interaction for SCO phenomena. We have investigated the cooperativity of the observed SCO phenomena. We have also studied the effect of Co doping on the spin state of Fe and find that the spin state of Fe has a subtle dependency on the concentration of dopant atoms. Excess Co doping pave the way towards the possibility of an intermediate spin state for Fe and can give rise to a bistable spin transition process.

Here we present the structural and magnetic properties of the new honeycomb material ${\mathrm{Ag}}_{3}{\mathrm{LiMn}}_{2}{\mathrm{O}}_{6}$. The system $\mathrm{Ag}[{\mathrm{Li}}_{1/3}{\mathrm{Mn}}_{2/3}]{\mathrm{O}}_{2}$ belongs to a quaternary $3R$-delafossite family and crystallizes in a monoclinic symmetry with space group $C\phantom{\rule{0.16em}{0ex}}2/m$, and the magnetic ${\mathrm{Mn}}^{4+}\phantom{\rule{0.28em}{0ex}}(S=3/2)$ ions form a honeycomb network in the $ab$ plane. An anomaly around 50 K and the presence of antiferromagnetic (AFM) coupling (Curie-Weiss temperature ${\ensuremath{\theta}}_{CW}\ensuremath{\sim}\ensuremath{-}51\phantom{\rule{0.28em}{0ex}}\mathrm{K}$) were inferred from our magnetic susceptibility data. The magnetic specific heat clearly manifests the onset of magnetic ordering in the vicinity of 48 K, and the recovered magnetic entropy, above the ordering temperature, falls short of the expected value, implying the presence of short-range magnetic correlations. An asymmetric Bragg peak (characteristic of two-dimensional order), seen in neutron diffraction, gains intensity even above the ordering temperature, thus showing the existence of short-range spin correlations. Our electron spin resonance (ESR) experiments corroborate the bulk magnetic data. Additionally, the ESR line broadening upon approaching the ordering temperature ${T}_{\mathrm{N}}$ could be described in terms of a Berezinskii-Kosterlitz-Thouless scenario with ${T}_{\mathrm{KT}}=40(1)\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. The $^{7}\mathrm{Li}$ NMR line shift probed as a function of temperature tracks the static susceptibility (${K}_{\mathrm{iso}}$) of magnetically coupled ${\mathrm{Mn}}^{4+}$ ions. The $^{7}\mathrm{Li}$ spin-lattice relaxation rate ($1/{T}_{1}$) exhibits a sharp decrease below about 50 K. A critical divergence is absent at the ordering temperature perhaps because of the filtering out of the antiferromagnetic fluctuations at the Li site, i.e., at the centers of the hexagons in the honeycomb network. Combining our bulk and local probe measurements, we establish the presence of an ordered ground state for the honeycomb system ${\mathrm{Ag}}_{3}{\mathrm{LiMn}}_{2}{\mathrm{O}}_{6}$. Our ab initio electronic structure calculations suggest that in the $ab$ plane, the nearest-neighbor (NN) exchange interaction is strong and AFM, while the next-NN and the third-NN exchange interactions are FM and AFM, respectively. The interplanar exchange interaction is found to be relatively small. In the absence of any frustration the system is expected to exhibit long-range, AFM order, in agreement with experiment.

We have investigated the thermodynamic and local magnetic properties of the Mott insulating system Ag$_{3}$LiRu$_{2}$O$_{6}$ containing Ru$^{4+}$ (4$d$$^{4}$) for novel magnetism. The material crystallizes in a monoclinic $C2/m$ structure with RuO$_{6}$ octahedra forming an edge-shared two-dimensional honeycomb lattice with limited stacking order along the $c$-direction. The large negative Curie-Weiss temperature ($\theta_{CW}$ = -57 K) suggests antiferromagnetic interactions among Ru$^{4+}$ ions though magnetic susceptibility and heat capacity show no indication of magnetic long-range order down to 1.8 K and 0.4 K, respectively. $^{7}$Li nuclear magnetic resonance (NMR) shift follows the bulk susceptibility between 120-300 K and levels off below 120 K. Together with a power-law behavior in the temperature dependent spin-lattice relaxation rate between 0.2 and 2 K, it suggest dynamic spin correlations with gapless excitations. Electronic structure calculations suggest an $S = 1$ description of the Ru-moments and the possible importance of further neighbour interactions as also bi-quadratic and ring-exchange terms in determining the magnetic properties. Analysis of our $\mu$SR data indicates spin freezing below 5 K but the spins remain on the borderline between static and dynamic magnetism even at 20 mK.

While it was speculated that $5{d}^{4}$ systems would possess nonmagnetic $J=0$ ground state due to strong spin-orbit coupling (SOC), all such systems have invariably shown the presence of magnetic moments so far. A puzzling case is that of ${\mathrm{Ba}}_{2}{\mathrm{YIrO}}_{6}$, which in spite of having a perfectly cubic structure with largely separated ${\mathrm{Ir}}^{5+}\phantom{\rule{4pt}{0ex}}({d}^{4})$ ions, has consistently hosted weak magnetic moments. We show from muon spin relaxation $(\ensuremath{\mu}\mathrm{SR})$ measurements that a change in the magnetic environment of the implanted muons in ${\mathrm{Ba}}_{2}{\mathrm{YIrO}}_{6}$ occurs as the temperature is lowered below 10 K indicating magnetic response has a temperature dependence unlikely for a $J=0$ system. Interestingly, the estimated value of SOC obtained by fitting the resonant inelastic x-ray scattering (RIXS) spectrum of ${\mathrm{Ba}}_{2}{\mathrm{YIrO}}_{6}$ with an effective atomic many-body Hamiltonian is found to be as high as 0.39 eV, comparable to the reported value of SOC in other magnetic ${d}^{4}$ iridates with noncubic distortion. We argue that in addition to strong SOC, the presence of intersite hopping triggers delocalization of holes, resulting in the spontaneous generation of magnetic moments. Our theoretical calculations further indicate that these moments favor the formation of spin-orbital singlets in the case of ${\mathrm{Ba}}_{2}{\mathrm{YIrO}}_{6}$, which is manifested in $\ensuremath{\mu}\mathrm{SR}$ experiments measured down to 60 mK.

Heavy metal pollution is an alarming problem for the ecosystem. Zinc (Zn) is one of the most common heavy metal contaminant in the environment. In recent years different, abatement strategies are being implemented to control metal pollutants, amongst these, bioremediation has gained substantial focus. This paper detailed the Zn uptake and removal efficacies of a Zn tolerant fungal strain, Aspergillus terreus (minimum inhibitory concentration against Zn being 9100 ppm) which was capable of removing 75–35 % Zn from different Zn enriched media. However, the uptake and removal efficacies were found to be decreased with increasing Zn concentrations. FTIR spectra showed involvement of functional groups (present on outer surface of fungal cell wall) in Zn adsorption. Concurrently, Zn decreased the activities of two important metabolic enzymes, CMCase and α-amylase. Scanning electron micrographs clearly demonstrated the structural deformation of fungal hyphae due to Zn exposure. To combat the Zn stress A. terreus upregulated its antioxidative defense system, which is reflected through the significant upregulation of superoxide dismutase and catalase enzyme activities and metal responsive protein (metallothionein) with respect to control.

The present study describes the potential of gamma rays in enhancing zinc tolerance of Aspergillus niger. Gamma exposed group of A. niger showed 1.82 times more zinc tolerance than the unirradiated ones. Gamma exposed A. niger grown in different zinc enriched media, showed increase in growth (expressed in terms of colony forming unit), higher efficiency in zinc uptake and removal, when compared to that of their unirradiated counterparts. The present investigation throws light towards utilizing gamma radiation for formulating more metal-tolerant fungi for bioremediation.

We have carried out a detailed first principles electronic structure calculations for d4 double perovskite iridates Ba2ScIrO6 and Sr2ScIrO6. Our calculations reveal that the ground state of both the systems to be magnetic contrary to the expectation of J eff = 0 nonmagnetic state induced by strong spin-orbit coupling. Our exact diagonalization calculation with two site many body Hamiltonian suggests that hopping induced delocalization of holes leads to the formation of local moments in these systems.

High spin states in $^{178}\mathrm{Os}$ were studied by means of $^{165}\mathrm{Ho}$($^{20}\mathrm{Ne}$,$p6n$)$^{178}\mathrm{Os}$ fusion evaporation reaction at a beam energy of 150 MeV, using a clover detector array. Several new transitions belonging to $^{178}\mathrm{Os}$ were placed in a level scheme and a new aligned rotational band was observed in addition to earlier known bands. Spin-parity assignments for most of the proposed levels were made using the deduced directional correlation orientation and polarization measurements for the de-exciting transitions. Experimental results are compared with the projected angular momentum deformed Hartree-Fock model calculations and cranked Woods-Saxon model calculations. This nucleus is predicted to be prolate deformed in the ground state but the $\ensuremath{\gamma}$-softness at higher excitation is revealed by the cranked Woods-Saxon model and the geometrical asymmetric model calculations.