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To search for a conceptual picture describing the magnetization plateau phenomenon, we surveyed the crystal structures and the spin lattices of those magnets exhibiting plateaus in their magnetization vs. magnetic field curves by probing the three questions: (a) why only certain magnets exhibit magnetization plateaus, (b) why there occur several different types of magnetization plateaus, and (c) what controls the widths of magnetization plateaus. We show that the answers to these questions lie in how the magnets under field absorb Zeeman energy hence changing their magnetic structures. The magnetic structure of a magnet insulator is commonly described in terms of its spin lattice, which requires the determination of the spin exchanges nonnegligible strengths between the magnetic ions. Our work strongly suggests that a magnet under magnetic field partitions its spin lattice into antiferromagnetic (AFM) or ferrimagnetic fragments by breaking its weak magnetic bonds. Our supposition of the field-induced partitioning of spin lattice into magnetic fragments is supported by the anisotropic magnetization plateaus of Ising magnets and by the highly anisotropic width of the 1/3-magnetization plateau in azurite. The answers to the three questions (a) - (c) emerge naturally by analyzing how these fragments are formed under magnetic field., Comment: A survey of the magnetization plateau phenomenon; 128 pages including the Supporting Information

Diamond single crystals showing Infra-red features of pressurized CO2-I phase were studied using Transmission Electron Microscopy (TEM) and tomography. Numerous O-containing precipitates with sizes up to 45 nm are observed. The absolute majority of these precipitates decorate dislocation loops or are located inside them; individual scattered precipitates are also present. Morphology of the precipitates varies from quasi-isometric octahedra to highly flattened elongated ones. Close association of the precipitates with the dislocation loops implies their formation by exsolution of oxygen impurity from diamond lattice; the size distribution of the precipitates suggests that the equilibrium state is not yet reached. Presumably, the morphology and precise chemical composition depend on P-T-t evolution of the diamond crystal and corresponding changes in oxygen supersaturation in the lattice. The CO2-containing diamonds often contain micron-sized hexagonal lamellar inclusions. TEM investigation of a lamellae reveals that it consists of high quality graphite showing partial epitaxial relation with comprising diamond. The gap between the graphite and diamond may be enriched with oxygen impurity.

We studied the low-temperature specific heats of two antiferromagnets with the two-dimensional square-kagome structure, i.e., KCu$_6$AlBiO$_4$(SO$_4$)$_5$Cl (KCu6) and Na$_6$Cu$_7$BiO$_4$(PO$_4$)$_4$[Cl,(OH)]$_3$ (NaCu7) with the structural differences that there are interlayer Cu$^{2+}$ ions in NaCu7. Both materials show no magnetic ordering down to 50 mK. At zero field, the $C/T$ of KCu6 has a finite value when the temperature is close to zero K. Under the magnetic field, a seemingly $T^2$ dependence appears and its coefficient is progressively suppressed by the field. For NaCu7, the specific heat exhibits the $T^2$ dependence at zero field and under fields. The ratio of the quadratic coefficients of KCu6 and NaCu7 at high fields is inversely proportional to ratio of the squared Weiss temperatures, which indicates these two compounds host the same ground state under fields. Our results suggest that the interlayer Cu$^{2+}$ ions in NaCu7 play a negligible role in determination of its ground state. We discuss the possible quantum-spin-liquid states in these compounds and further directions to pursue based our results., Comment: 5 pages, 3 figures

We compare the upper critical field of bulk single-crystalline samples of the two intrinsic transition metal dichalcogenide (TMD) superconductors, 2H-NbSe2 and 2H-NbS2, in high magnetic fields where their layer structure is aligned strictly parallel and perpendicular to the field, using magnetic torque experiments and a high-precision piezo-rotary positioner. While both superconductors show that orbital effects still have a significant impact when the layer structure is aligned parallel to the field, the upper critical field of NbS2 rises above the Pauli limiting field and forms a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, while orbital effects suppress superconductivity in NbSe2 just below the Pauli limit. From the out-of-plane anisotropies, the coherence length perpendicular to the layers of 31 {\AA} in NbSe2 is much larger than the interlayer distance, leading to a significant orbital effect suppressing superconductivity before the Pauli limit is reached, in contrast to the more 2D NbS2.

We report on a combined experimental and theoretical study on CrI3 single crystals by employing the polarization dependence of resonant inelastic X-ray scattering (RIXS). Our investigations reveal multiple Cr 3d orbital splitting (dd excitations) as well as magnetic dichroism (MD) in the RIXS spectra which is evidence of spin-flip in the dd excitation. Interestingly, the dd excitation energies are similar on both sides of the ferromagnetic transition temperature, TC of 61 K, although MD in RIXS is predominant at 0.4 tesla magnetic field below TC. This demonstrates that the ferromagnetic superexchange interaction that is responsible for the intra-atomic exchange field, is vanishingly small compared to local exchange field that comes from exchange and correlation interaction among the interacting Cr 3d orbitals. The investigation presented here demonstrate that the electronic structure of bulk CrI3 is complex in the sense that dynamical electron correlations are significant. The recorded RIXS spectra reported here reveal clearly resolved Cr 3d intra-orbital dd excitations that represent transitions between electronic levels that are heavily influenced by multi-configuration effects. Our calculations employing the crystal field TTmultiplet theory taking into account the Cr 3d hybridization with the ligand valence states and the full multiplet structure due to intra-atomic and crystal field interactions in Oh and D3d symmetry, clearly reproduced the dichroic trend in experimental RIXS spectra., Comment: 7 pages, 4 figures

The magnetic nature of low dimensional compound, CrCl$_3$, was investigated by muon spin rotation, relaxation and resonance ($\mu^+$SR). The $\mu^+$SR measurements revealed three distinct phases as a function of temperature: an antiferromagnetic state (AF) for $T\leq T_{\rm N}=14.32(6)$~K, a ferromagnetic short range ordered state (FM-SRO) for $T_{\rm N}

Antiferromagnetic PbMnTeO6, also known as mineral kuranakhite, has been reported recently to have all three cations in trigonal prismatic coordination, which is extremely unusual for both Mn(4+) and Te(6+). In this work, the phase was reproduced with the same lattice parameters and N\'eel temperature TN = 20 K. However, powder neutron diffraction unambiguously determined octahedral (trigonal antiprismatic) coordination for all cations within the chiral space group P312. The same symmetry was proposed for SrMnTeO6 and PbGeTeO6, instead of the reported space groups P-62m and P31m, respectively. PbMnTeO6 was found to be a robust antiferromagnet with an assumingly substantial scale of exchange interactions since the Neel temperature did not show any changes in external magnetic fields up to 7 T. The determined effective magnetic moment meff = 3.78 mB was in excellent agreement with the numerical estimation using the effective g-factor g = 1.95 directly measured here by electron spin resonance (ESR). Both specific heat and ESR data indicated the two-dimensional character of magnetism in the compound under study. The combination of chirality with magnetic order makes PbMnTeO6 a promising material with possible multiferroic properties.

Single-domain particles of SrFe8Al4O19 were prepared by thermal treatment at 1473 K of porous products of citrate-nitrate auto-combustion, and the influence of synthesis time on the particle morphology and magnetic properties was studied. The procedure allows to obtain SrFe8Al4O19 particles with mean diameters 100 - 460 nm, and their coercivity ranges from 14.5 to 18.4 kOe, while ferromagnetic resonance frequencies vary from 149 to 164 GHz.

The strong fascination exerted by the binary compound of FeSe demands reliable engineering protocols and more effective approaches towards inducing superconductivity in FeSe thin films. Our study addresses the peculiarities in pulsed laser deposition which determine FeSe thin film growth and focuses on the film/substrate interface, the tendency for domain matching epitaxial growth but also the disadvantage of chemical heterogeneity. We propose that homogenization of the substrate surface improves the control of stoichiometry, texture, and nanostrain in a way that favors superconductivity even in ultrathin FeSe films. The controlled interface in FeSe/Fe/MgO demonstrates the proof-of-principle., Comment: Submitted

Polyhydrides offer intriguing perspectives as high-temperature superconductors. Here we report the high-pressure synthesis of a series of lanthanum-yttrium ternary hydrides: cubic hexahydride $(La,Y)H_{6}$ with a critical temperature $T_{C}$ = 237 +/- 5 K and decahydrides $(La,Y)H_{10}$ with a maximum $T_{C}$ ~${253 K}$ and an extrapolated upper critical magnetic field $B_{C2(0)}$ up to ${135 T}$ at 183 GPa. This is one of the first examples of ternary high-$T_{C}$ superconducting hydrides. Our experiments show that a part of the atoms in the structures of recently discovered ${Im3m}$-$YH_{6}$ and ${Fm3m}$-$LaH_{10}$ can be replaced with lanthanum (~70 %) and yttrium (~25 %), respectively, with a formation of unique ternary superhydrides containing incorporated $La@H_{24}$ and $Y@H_{32}$ which are specific for ${Im3m}$-$LaH_{6}$ and ${Fm3m}$-$YH_{10}$. Ternary La-Y hydrides were obtained at pressures of 170-196 GPa via the laser heating of $P6_{3}$${/mmc}$ lanthanum-yttrium alloys in the ammonia borane medium at temperatures above 2000 K. A novel tetragonal $(La,Y)H_{4}$ was discovered as an impurity phase in synthesized cubic $(La,Y)H_{6}$. The current-voltage measurements show that the critical current density $J_{C}$ in $(La,Y)H_{10}$ may exceed $2500 A/mm^{2}$ at 4.2 K, which is comparable with that for commercial superconducting wires such as ${NbTi}$, $Nb_{3}$${Sn}$. Hydrides that are unstable in a pure form may nevertheless be stabilized at relatively low pressures in solid solutions with superhydrides having the same structure.

A new oxide, sodium iron antimonate, Na2FeSbO5, was synthesized and structurally characterized, and its static and dynamic magnetic properties were comprehensively studied both experimentally by dc and ac magnetic susceptibility, magnetization, specific heat, electron spin resonance (ESR) and Moessbauer measurements, and theoretically by density functional calculations. The resulting single-crystal structure (a = 15.6991(9) A; b = 5.3323 (4) A; c = 10.8875(6) A; S.G. Pbna) consists of edge-shared SbO6 octahedral chains, which alternate with vertex-linked, magnetically active FeO4 tetrahedral chains. The 57Fe Moessbauer spectra confirmed the presence of high-spin Fe3+ (3d5) ions in a distorted tetrahedral oxygen coordination. The magnetic susceptibility and specific heat data show the absence of a long-range magnetic ordering in Na2FeSbO5 down to 2 K, but ac magnetic susceptibility unambigously demonstrates spin-glass-type behavior with a unique two-step freezing at Tf1 about 80 K and Tf2 about 35 K. Magnetic hyperfine splitting of 57Fe Moessbauer spectra was observed below T* about 104 K (Tf1 < T*). The spectra just below T* (Tf1 < T < T*) exhibit a relaxation behavior caused by critical spin fluctuations, indicating the existence of short-range correlations. The stochastic model of ionic spin relaxation was used to account for the shape of the Moessbauer spectra below the freezing temperature. A complex slow dynamics is further supported by ESR data revealing two different absorption modes presumably related to ordered and disordered segments of spin chains. The data imply a spin-cluster ground state for Na2FeSbO5.

In the paper, we investigate two problems on strings. The first one is the String matching problem, and the second one is the String comparing problem. We provide a quantum algorithm for the String matching problem that uses exponentially less quantum memory than existing ones. The algorithm uses the hashing technique for string matching, quantum parallelism, and ideas of Grover's search algorithm. Using the same ideas, we provide two algorithms for the String comparing problem. These algorithms also use exponentially less quantum memory than existing ones. Additionally, the second algorithm works exponentially faster than the existing one., Comment: 13 pages

An orthorhombic compound, NaMnSbO4, represents a square net of magnetic Mn2+ ions residing in vertex-shared oxygen octahedra. Its static and dynamic magnetic properties were studied using magnetic susceptibility, specific heat, magnetization, electron spin resonance (ESR), nuclear magnetic resonance (NMR) and density functional calculations. Thermodynamic data indicate an establishment of the long-range magnetic order with TN about 44 K, which is preceded by a short-range one at about 55 K. In addition, a non-trivial wasp-waisted hysteresis loop of the magnetization was observed, indicating that the ground state is most probably canted antiferromagnetic. Temperature dependence of the magnetic susceptibility is described reasonably well in the framework of 2D square lattice model with the main exchange parameter J = -5.3 K, which is in good agreement with density functional analysis, NMR and ESR data.

Due to their physical properties and potential applications in energy conversion and storage, transition metal dichalcogenides (TMDs) have garnered substantial interest in recent years. Amongst this class of materials, TMDs based on molybdenum, tungsten, sulfur and selenium are particularly attractive due to their semiconducting properties and the availability of bottom-up synthesis techniques. Here we report a method which yields high quality crystals of transition metal diselenide and ditelluride compounds (PtTe2, PdTe2, NiTe2, TaTe2, TiTe2, RuTe2, PtSe2, PdSe2, NbSe2, TiSe2, VSe2, ReSe2) from their solid solutions, via vapor deposition from a metal-saturated chalcogen melt. Additionally, we show the synthesis of rare-earth metal poly-chalcogenides and NbS2 crystals using the aforementioned process. Most of the obtained crystals have a layered CdI2 structure. We have investigated the physical properties of selected crystals and compared them to state-of-the-art findings reported in the literature. Remarkably, the charge density wave transition in 1T-TiSe2 and 2H-NbSe2 crystals is well-defined at TCDW ~ 200 K and ~ 33 K, respectively. Angle-resolved photoelectron spectroscopy and electron diffraction are used to directly access the electronic and crystal structures of PtTe2 single crystals, and yield state-of-the-art measurements., Comment: 12 pages, 10 figures