A pyroxene-based quantum magnet with multiple magnetization plateaus.

Pyroxenes (AMXO) consisting of infinite one-dimensional edge-sharing MO chains and bridging XO tetrahedra are fertile ground for finding quantum materials. Thus, here, we have studied calcium cobalt germanate (CaCoGeO) and calcium cobalt silicate (CaCoSiO) crystals in depth. Heat capacity data show that the spins in both compounds are dominantly Ising-like, even after being manipulated by high magnetic fields.

Out-of-equilibrium charge redistribution in a copper-oxide based superconductor by time-resolved X-ray photoelectron spectroscopy.

Charge-transfer excitations are of paramount importance for understanding the electronic structure of copper-oxide based high-temperature superconductors. In this study, we investigate the response of a Bi Sr CaCu O crystal to the charge redistribution induced by an infrared ultrashort pulse. Element-selective time-resolved core-level photoelectron spectroscopy with a high energy resolution allows disentangling the dynamics of oxygen ions with different coordination and bonds thanks to their different chemical shifts.

Diamond surface functionalization via visible light-driven C-H activation for nanoscale quantum sensing.

Nitrogen-vacancy (NV) centers in diamond are a promising platform for nanoscale NMR sensing. Despite significant progress toward using NV centers to detect and localize nuclear spins down to the single spin level, NV-based spectroscopy of individual, intact, arbitrary target molecules remains elusive. Such sensing requires that target molecules are immobilized within nanometers of NV centers with long spin coherence.

Superconductivity-Electron Count Relationship in Heusler Phases-the Case of LiPdSi.

We report superconductivity in the full Heusler compound LiPdSi (space group , No. 225) at a critical temperature of = 1.3 K and a normalized heat capacity jump at , Δ/γ = 1.

Is LaNiO a Bulk Superconducting Nickelate?

Superconducting states onsetting at moderately high temperatures have been observed in epitaxially stabilized NiO-based thin films. However, recently, it has also been reported that superconductivity at high temperatures is observed in bulk LaNiO at high pressure, opening further possibilities for study. Here we report the reduction profile of LaNiO in a stream of 5% H/Ar gas and the isolation of the metastable intermediate phase LaNiO, which is based on Ni.

Entropy driven incommensurate structures in the frustrated kagome staircase CoVO.

CoVOfeatures spin-3/2 moments arrayed on a kagome staircase lattice. A spin density wave with a continuously evolving propagation vector ofk⃗=(0,δ,0), showing both incommensurate states and multiple commensurate lock-ins, is observed at temperatures above the ferromagnetic ground state. Previous work has suggested that this changing propagation vector could be driven by changes in exchange interactions due to Co atom displacements.

Evidence of Temperature-Dependent Interplay between Spin and Orbital Moment in van der Waals Ferromagnet VI.

van der Waals materials provide a versatile toolbox for the emergence of new quantum phenomena and fabrication of functional heterostructures. Among them, the trihalide VI stands out for its unique magnetic and structural landscape. Here we investigate the spin and orbital magnetic degrees of freedom in the layered ferromagnet VI by means of temperature-dependent X-ray absorption spectroscopy and X-ray magnetic circular and linear dichroism.

Ferromagnetic Coupling in Quasi-One-Dimensional Hybrid Iron Chloride Hexagonal Perovskites.

We synthesize four novel quasi-one-dimensional organic-inorganic hybrid iron chloride compounds (CHNHFeCl, CH(NH)FeCl, C(NH)FeCl, and CHNFeCl) and characterize their structural and magnetic properties. These materials crystallize in a hexagonal perovskite-type structure, constituting a triangular array of face-sharing iron chloride octahedra chains running along the -axis, isolated from one another by the organic cation. Through magnetization and heat capacity measurements, we find that the intrachain coupling is weakly ferromagnetic for each variant.

The pressure-stabilized polymorph of indium triiodide.

A layered rhombohedral polymorph of indium(III) triiodide is synthesized at high pressure and temperature. The unit cell symmetry and approximate dimensions are determined by single crystal X-ray diffraction. Its 3̄ crystal structure, with = 7.

Stuffed Rare-Earth Garnets.

We report the synthesis and magnetic characterization of stuffed rare-earth gallium garnets, REGaO (RE = Lu, Yb, Er, Dy, Gd), for up to 0.5. The excess rare-earth ions partly fill the octahedral sites normally fully occupied by Ga, forming disordered pairs of corner-shared face-sharing magnetic tetrahedra.

Evidence for two dimensional anisotropic Luttinger liquids at millikelvin temperatures.

Interacting electrons in one dimension (1D) are governed by the Luttinger liquid (LL) theory in which excitations are fractionalized. Can a LL-like state emerge in a 2D system as a stable zero-temperature phase? This question is crucial in the study of non-Fermi liquids. A recent experiment identified twisted bilayer tungsten ditelluride (tWTe) as a 2D host of LL-like physics at a few kelvins.

Impersonating a Superconductor: High-Pressure BaCoO, an Insulating Ferromagnet.

We report the high-pressure synthesis (6 GPa, 1200 °C) and ambient-pressure characterization of hexagonal HP-BaCoO. The material (with a 2H crystal structure) has a short intrachain Co-Co distance of about 2.07 Å.

Indistinguishable telecom band photons from a single Er ion in the solid state.

Atomic defects in the solid state are a key component of quantum repeater networks for long-distance quantum communication. Recently, there has been significant interest in rare earth ions, in particular Er for its telecom band optical transition that allows long-distance transmission in optical fibres. However, the development of repeater nodes based on rare earth ions has been hampered by optical spectral diffusion, precluding indistinguishable single-photon generation.

Erbium-Excess Gallium Garnets.

A series of garnets of formula ErGaO are described, for which we report the crystal structures for both polycrystalline and single-crystal samples. The limit in the garnet phase is between 0.5 and 0.

Phonon Anharmonicity and Spin-Phonon Coupling in CrI.

We report on the far-infrared, temperature-dependent optical properties of a CrI3 transition metal halide single crystal, a van der Waals ferromagnet (FM) with a Curie temperature of 61 K. In addition to the expected phonon modes determined by the crystalline symmetry, the optical reflectance and transmittance spectra of CrI3 single crystals show many other excitations as a function of temperature as a consequence of the combination of a strong lattice anharmonicity and spin-phonon coupling. This complex vibrational spectrum highlights the presence of entangled interactions among the different degrees of freedom in CrI3.

Chemical Profiles of the Oxides on Tantalum in State of the Art Superconducting Circuits.

Over the past decades, superconducting qubits have emerged as one of the leading hardware platforms for realizing a quantum processor. Consequently, researchers have made significant effort to understand the loss channels that limit the coherence times of superconducting qubits. A major source of loss has been attributed to two level systems that are present at the material interfaces.

Neutral Silicon Vacancy Centers in Undoped Diamond via Surface Control.

Neutral silicon vacancy centers (SiV^{0}) in diamond are promising candidates for quantum applications; however, stabilizing SiV^{0} requires high-purity, boron-doped diamond, which is not a readily available material. Here, we demonstrate an alternative approach via chemical control of the diamond surface. We use low-damage chemical processing and annealing in a hydrogen environment to realize reversible and highly stable charge state tuning in undoped diamond.

Electron doping of a double-perovskite flat-band system.

Electronic structure calculations indicate that the SrFeSbO double perovskite has a flat-band set just above the Fermi level that includes contributions from ordinary subbands with weak kinetic electron hopping plus a flat subband that can be attributed to the lattice geometry and orbital interference. To place the Fermi energy in that flat band, electron-doped samples with formulas SrLaFeSbO (0 ≤ ≤ 0.3) were synthesized, and their magnetism and ambient temperature crystal structures were determined by high-resolution synchrotron X-ray powder diffraction.

Chemical Pressure Tuning Magnetism from Pyrochlore to Triangular Lattices.

Geometrically frustrated lattices combined with magnetism usually host quantum fluctuations that suppress magnetic orders and generate highly entangled ground states. Three-dimensionally (3D) frustrated magnets generally exist in the diamond and pyrochlore lattices, while two-dimensionally (2D) frustrated geometries contain Kagomé, triangular, and honeycomb lattices. In this work, we reported using chemical pressure to tune the magnetism of the pyrochlore lattice in LiYbSe into a triangular lattice by doping Ga or In.

Tuning the Band Gap in the Halide Perovskite CsPbBr through Sr Substitution.

The ability to continuously tune the band gap of a semiconductor allows its optical properties to be precisely tailored for specific applications. We demonstrate that the band gap of the halide perovskite CsPbBr can be continuously widened through homovalent substitution of Sr for Pb using solid-state synthesis, creating a material with the formula CsPbSrBr (0 ≤ ≤ 1). Sr and Pb form a solid solution in CsPbSrBr.

Antiferromagnetic to Ferromagnetic Coupling Crossover in Hybrid Nickel Chain Perovskites.

We synthesize and characterize the magnetic and thermodynamic properties of the quasi one-dimensional organic-inorganic hybrid ANiCl compounds [A = N(CH), CHNH, (CH)NH, C(NH), and CH(NH)]. Additionally, the crystal structure of (CH)NHNiCl is reported. These materials possess chains of face-sharing NiCl octahedra in a triangular array.