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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on YCu(WO4)2 by Materials Project

YCu(WO4)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Y3+ is bonded to six O2- atoms to form YO6 octahedra that share corners with eight WO6 octahedra. The corner-sharing octahedra tilt angles range from 34–54°. There are a spread of Y–O bond distances ranging from 2.28–2.33 Å. There are two inequivalent W6+ sites. In the first W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with four equivalent YO6 octahedra and edges with two equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 34–54°. There are a spread of W–O bond distances ranging from 1.82–2.19 Å. In the second W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with four equivalent YO6 octahedra and edges with two equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 34–54°. There are a spread of W–O bond distances ranging from 1.82–2.19 Å. Cu1+ is bonded in a distorted linear geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.85–2.70 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one W6+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Y3+, one W6+, and one Cu1+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two W6+ and one Cu1+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Y3+ and two W6+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Y3+, one W6+, and one Cu1+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one W6+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Y3+ and two W6+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two W6+ and one Cu1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YCu by Materials Project

YCu is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Y is bonded in a body-centered cubic geometry to eight equivalent Cu atoms. All Y–Cu bond lengths are 3.01 Å. Cu is bonded in a body-centered cubic geometry to eight equivalent Y atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1995

The Low-Lying Electronic States of YCu

The spectroscopic constants for the singlet and triplet states of YCu below about 15 000 per centimeter are determined using an internally contracted multireference configuration-interaction approach. These calculations are calibrated by studies of fewer states using higher levels of correlation treatment and/or larger basis sets. The computed T(sub e) values and radiative lifetimes are in reasonable agreement with experiment. The calculations confirm the previous experimental assignment for all but one state, where theory helps resolve between two possible assignments.

Ricca, Alessandra↗
DOE OSTI2020

Materials Data on YCu(WO4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2025

Thermodynamic Evidence of Fermionic Behavior in the Vicinity of One-Ninth Plateau in a Kagome Antiferromagnet

The spin-1/2 kagome Heisenberg antiferromagnets are believed to host exotic quantum entangled states. Recently, the reports of 1/9 magnetization plateau and magnetic oscillations in a kagome antiferromagnet YCu 3 ⁢(OH) 6 ⁢Br 2 ⁢[Br 𝑥 ⁢(OH) 1−𝑥 ] (YCOB) have made this material a promising candidate for experimentally realizing quantum spin liquid states. Here, we present measurements of the specific heat 𝐶 𝑝 in YCOB in high magnetic fields (up to 41.5 T) down to 0.46 K, and the 1/9 plateau feature has been confirmed. Moreover, the temperature dependence of 𝐶 𝑝 /𝑇 in the vicinity of 1/9 plateau region can be fitted by a linear in 𝑇 term which indicates the presence of a Dirac spectrum, together with a constant term, which indicates a finite density of states contributed by other spinon Fermi surfaces. Surprisingly, the constant term is highly anisotropic in the direction of the magnetic field. Additionally, we observe a double-peak feature near 30 T above the 1/9 plateau which is another hallmark of fermionic excitations in the specific heat. This combination of gapless behavior and the double-peak structure strongly suggests that the 1/9 plateau in YCOB is nontrivial and hosts fermionic quasiparticles.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Cyclotron resonance in a kagome spin liquid candidate material

We propose cyclotron resonance as an optical probe for emergent fractionalized excitations in U⁡(1) quantum spin liquids, focusing on kagome antiferromagnets. In contrast to conventional systems, where cyclotron resonance directly couples to charged carriers, spinons in spin liquids are charge-neutral and interact only through an emergent gauge field, making direct probing challenging. We identify two key mechanisms by which an external physical electromagnetic field induces emergent electric and magnetic fields, enabling indirect coupling to spinons. Using these mechanisms, we compute the absorption rate of the cyclotron resonance response for Dirac spinons forming Landau levels. Our analysis shows that, although the absorption per layer is small, the absence of a skin-depth limitation in insulating spin liquids allows for cumulative absorption comparable to graphene in realistic sample sizes for the recently discovered spin-liquid candidate material YCu 3⁢ (OH) 6⁢ Br 2 ⁢[Br 1−𝑦 ⁢(OH) 𝑦 ]. Furthermore, our proposed cyclotron-resonance measurement is a decisive, practical test for spinon Landau levels, providing quantitative expectations where clear experimental evidence has so far been lacking.

Dzyaloshinskii-Moriya interaction↗
DOE OSTI2026

Dirac Node Pinning from Dzyaloshinskii-Moriya Interactions in a Kagome Spin Liquid

Recent experiments on the Kagome spin liquid candidate material YCu 3 ⁢(OH) 6 ⁢Br 2 ⁢[Br 1−𝑦 ⁢(OH) 𝑦 ] suggest the presence of Dirac fermionic spinons near the magnetization plateau at 1/9. Theories suggest that the spinons are charge neutral spin-1/2 excitations, in a 2⁢𝜋/3 flux, which triples the unit cell. Generally a gap is expected, and there is no symmetry protection for the Dirac nodes in this system. The question arises as to what causes the nodes and stabilizes them. In this work, we propose a node-creation and node-pinning mechanism driven by Dzyaloshinskii-Moriya (DM) interactions. Employing Gutzwiller-projected variational Monte Carlo calculations, we demonstrate that DM interactions induce a band closing phase transition in the spinon spectrum. There is a change in the Chern number when the bands are inverted. Together with the DM-generated internal gauge flux, the coupling to the spinon orbital magnetization counteracts the band reopening. Furthermore, this interplay energetically pins the Dirac nodes over a range of parameters, resulting in a pinning mechanism distinct from the usual one from symmetry protection.

Kagome lattice↗
DOE OSTI2026

Disorder-induced spin-cluster magnetism in a doped kagome spin liquid candidate

The search for new quantum spin liquid materials relies on systems with strong frustration such as spins on an ideal kagome lattice. However, lattice imperfections can have substantial effects which are as yet not well understood. In recent work, the two-dimensional kagome system YCu 3 ⁢(OH) 6 ⁢[(Cl 𝑥 ⁢Br (1−𝑥) ) 3−𝑦 ⁢(OH) 𝑦 ] has emerged as a leading candidate hosting a Dirac spin liquid which appears to survive at least for 𝑥 < 0.4, associated with alternating-bond-hexagon (ABH) disorder. Here in magnetic samples with 𝑥 = 0.58, 𝑦 = 0.1 we report unusual in-plane ferromagnetic canting (FM) of the in-plane antiferromagnet (AFM), with an unusually wide regime of short-ranged order, and propose theoretical models to explain this behavior. First, we show that Kitaev-type exchanges naturally arise on the kagome lattice to second order in the known Dzyaloshinskii-Moriya exchanges, and that these interactions can produce the unusual in-plane FM canting from antichiral AFM. Second, we propose a phenomenological model of weakly FM-canted spin clusters to describe the short-ranged regime and analyze quantum fluctuations in an ABH toy model to show how ABH disorder can stabilize this regime. Here, the combination of experimental observation and theory suggests that kagome-Kitaev interactions and ABH disorder are necessary for describing the magnetic fluctuations in this family of materials, with potential implications for the proposed proximate spin liquid phase.

Seth, Arnab [Georgia Institute of Technology, Atla↗