One of the cornerstone effects in spintronics is spin pumping by dynamical magnetization that is steadily precessing (around, for example, the
The anomalous Hall effect (AHE), typically observed in ferromagnetic (FM) metals with broken timereversal symmetry, depends on electronic and magnetic properties. In Co_{3}Sn_{2x}In_{x}S_{2}, a giant AHE has been attributed to Berry curvature associated with the FM Weyl semimetal phase, yet recent studies report complicated magnetism. We use neutron scattering to determine the spin dynamics and structures as a function of
 Award ID(s):
 2100741
 NSFPAR ID:
 10466674
 Publisher / Repository:
 npj Quantum Materials
 Date Published:
 Journal Name:
 npj Quantum Materials
 Volume:
 7
 Issue:
 1
 ISSN:
 23974648
 Page Range / eLocation ID:
 112
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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Abstract z axis) with frequencyω _{0}due to absorption of lowpower microwaves of frequencyω _{0}under the resonance conditions and in the absence of any applied bias voltage. The twodecadesold ‘standard model’ of this effect, based on the scattering theory of adiabatic quantum pumping, predicts that component of spin current vector ${I}^{{S}_{z}}$ is timeindependent while $({I}^{{S}_{x}}(t),{I}^{{S}_{y}}(t),{I}^{{S}_{z}})\propto {\omega}_{0}$ and ${I}^{{S}_{x}}(t)$ oscillate harmonically in time with a single frequency ${I}^{{S}_{y}}(t)$ω _{0}whereas pumped charge current is zero in the same adiabatic $I\equiv 0$ limit. Here we employ more general approaches than the ‘standard model’, namely the timedependent nonequilibrium Green’s function (NEGF) and the Floquet NEGF, to predict unforeseen features of spin pumping: namely precessing localized magnetic moments within a ferromagnetic metal (FM) or antiferromagnetic metal (AFM), whose conduction electrons are exposed to spin–orbit coupling (SOC) of either intrinsic or proximity origin, will pump both spin $\propto {\omega}_{0}$ and charge ${I}^{{S}_{\alpha}}(t)$I (t ) currents. All four of these functions harmonically oscillate in time at both even and odd integer multiples of the driving frequency $N{\omega}_{0}$ω _{0}. The cutoff order of such high harmonics increases with SOC strength, reaching in the onedimensional FM or AFM models chosen for demonstration. A higher cutoff ${N}_{\mathrm{m}\mathrm{a}\mathrm{x}}\simeq 11$ can be achieved in realistic twodimensional (2D) FM models defined on a honeycomb lattice, and we provide a prescription of how to realize them using 2D magnets and their heterostructures. ${N}_{\mathrm{m}\mathrm{a}\mathrm{x}}\simeq 25$ 
Abstract The crystal structure and bonding environment of K_{2}Ca(CO_{3})_{2}bütschliite were probed under isothermal compression via Raman spectroscopy to 95 GPa and single crystal and powder Xray diffraction to 12 and 68 GPa, respectively. A second order BirchMurnaghan equation of state fit to the Xray data yields a bulk modulus,
GPa with an imposed value of$${K}_{0}=46.9$$ ${K}_{0}=46.9$ for the ambient pressure phase. Compression of bütschliite is highly anisotropic, with contraction along the$${K}_{0}^{\prime}= 4$$ ${K}_{0}^{\prime}=4$c axis accounting for most of the volume change. Bütschliite undergoes a phase transition to a monoclinicC 2/m structure at around 6 GPa, mirroring polymorphism within isostructural borates. A fit to the compression data of the monoclinic phase yields Å^{3}$${V}_{0}=322.2$$ ${V}_{0}=322.2$$$,$$ $,$ GPa and$${K}_{0}=24.8$$ ${K}_{0}=24.8$ using a third order fit; the ability to access different compression mechanisms gives rise to a more compressible material than the lowpressure phase. In particular, compression of the$${K}_{0}^{\prime}=4.0$$ ${K}_{0}^{\prime}=4.0$C 2/m phase involves interlayer displacement and twisting of the [CO_{3}] units, and an increase in coordination number of the K^{+}ion. Three more phase transitions, at ~ 28, 34, and 37 GPa occur based on the Raman spectra and powder diffraction data: these give rise to new [CO_{3}] bonding environments within the structure. 
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