39 research outputs found
Cavity-Magnon-Polariton spectroscopy of strongly hybridized electro-nuclear spin excitations in LiHoF4
We first present a formalism that incorporates the input-output formalism and
the linear response theory to employ cavity-magnon-polariton coupling as a
spectroscopic tool for investigating strongly hybridized electro-nuclear spin
excitations. A microscopic relation between the generalized susceptibility and
the scattering parameter |S11| in strongly hybridized cavity-magnon-polariton
systems has been derived without resorting to semi-classical approximations.
The formalism is then applied to both analyze and simulate a specific systems
comprising a model quantum Ising magnet (LiHoF4) and a high-finesse 3D
re-entrant cavity resonator. Quantitative information on the electro-nuclear
spin states in LiHoF4 is extracted, and the experimental observations across a
broad parameter range were numerically reproduced, including an external
magnetic field titraversing a quantum critical point. The method potentially
opens a new avenue not only for further studies on the quantum phase transition
in LiHoF4 but also for a wide range of complex magnetic systems.Comment: 16 pages, 8 figure
Doping Dependence of the in-Plane Transition in CoSnS
In CoSnS two transitions are observed, the main one to a
ferromagnetic state at K and the second one, involving in-plane
components at K. We follow their doping dependence as Sn is
replaced with In, which causes a reduction of and . Importantly,
both transitions follow the same doping dependence, indicating a single energy
scale involved with both processes.Comment: accepted as a short note in JPSJ; a continuation of work published in
arXiv:2211.01483 and https://doi.org/10.1103/PhysRevB.106.L18040
Unravelling the origin of the peculiar transition in the magnetically ordered phase of the Weyl semimetal Co3Sn2S2
Recent discovery of topologically non-trivial behavior in Co3Sn2S2 stimulated
a notable interest in this itinerant ferromagnet (Tc = 174 K). The exact
magnetic state remains ambiguous, with several reports indicating the existence
of a second transition in the range 125 -- 130 K, with antiferromagnetic and
glassy phases proposed to coexist with the ferromagnetic phase. Using detailed
angle-dependent DC and AC magnetization measurements on large, high-quality
single crystals we reveal a highly anisotropic behavior of both static and
dynamic response of Co3Sn2S2. It is established that many observations related
to sharp magnetization changes when B || c are influenced by the
demagnetization factor of a sample. On the other hand, a genuine transition has
been found at Tp = 128 K, with the magnetic response being strictly
perpendicular to the c-axis and several orders of magnitude smaller than for B
|| c. Calculations using density-functional theory indicate that the ground
state magnetic structure consist of magnetic moments canted away from the
c-axis by a small angle (~ 1.5deg). We argue that the second transition
originates from a small additional canting of moments within the kagome plane,
with two equivalent orientations for each spin.Comment: accepted as a Letter in PR
Correction: Facile N-functionalization and strong magnetic communication in a diuranium(v) bis-nitride complex (vol 10, pg 3543, 2019)
Correction for Facile N-functionalization and strong magnetic communication in a diuranium(v) bis-nitride complex' by Luciano Barluzzi et al., Chem. Sci., 2019, DOI: ; 10.1039/c8sc05721d
Triplons, Magnons, and Spinons in a Single Quantum Spin System: SeCuO3
Quantum spin systems exhibit an enormous range of collective excitations, but
their spin waves, gapped triplons, fractional spinons, or yet other modes are
generally held to be mutually exclusive. Here we show by neutron spectroscopy
on SeCuO that magnons, triplons, and spinons are present simultaneously. We
demonstrate that this is a consequence of a structure consisting of two coupled
subsystems and identify all the interactions of a minimal magnetic model. Our
results serve qualitatively to open the field of multi-excitation spin systems
and quantitatively to constrain the complete theoretical description of one
member of this class of materials.Comment: 8 pages, 5 figure
Critical scaling in the cubic helimagnet Cu2OSeO3
We present a detailed ac susceptibility investigation of the fluctuation regime in the insulating cubic helimagnet Cu2OSeO3. For magnetic fields mu H-0 >= 200 mT, and over a wide temperature (T) range, the system behaves according to the scaling relations characteristic of the classical three-dimensional Heisenberg model. For lower magnetic fields, the scaling is preserved only at higher T and becomes renormalized in a narrow-T range above the transition temperature. Contrary to the well-studied case of MnSi, where the renormalization has been interpreted within the Brazovskii theory, our analysis of the renormalization at H = 0 shows the fluctuation regime in Cu2OSeO3 to lie closer to that expected within the Wilson-Fischer scenario
FeOx magnetization enhancing E-coli inactivation by orders of magnitude on Ag-TiO2 nanotubes under sunlight
Drastic bacterial enhancement was observed when the Ag(3%)-TiO2 nanotubes were modified with FeOx (3%) magnetic oxide. On bare TiO2- nanotubes a reduction of 0.21og(10)CFU was observed within one hour under simulated low intensity solar light. Under similar conditions, a bacterial reduction of 2.5log(10)CFU was observed, on Ag(3%)TiO2 increasing to 6.0log(10)CFU on Ag(3%)-TiO2-FeOx(3%) magnetic nanotubes. The bacterial inactivation kinetics is strongly influenced by the addition of FeOx. The fast inactivation induced by the composite catalyst seems to involve an increase in the interfacial charge transfer (IFCT) compared to a 2-oxide composite photocatalyst. Stable recycling of the photocatalyst was observed leading to bacterial oxidation. The unambiguous identification of the radical intermediates: OH-radicals, O-singlet and the valence holes vb(h +) on the Ag-TiO2-FeOx interface showed that the valence band holes vb(h +) were the main oxidative intermediates leading to bacterial inactivation. Nanotubes size, crystallinity and bulk composition of magnetite 1% (0 = 51.0 degrees), anatase 5% (0 = 8.9 degrees), goethite 37.3% (0 = 9.0 degrees), silver 1% (0=2.7 degrees) was obtained by the Rietveld refinement for the Ag(3%)-TiO2-FeOx(3%) nanotubes. The redox chemistry during bacterial inactivation was determined by X-ray photoelectron spectroscopy (XPS). (C) 2016 Elsevier B.V. All rights reserved
Magnetic nano-fluctuations in a frustrated magnet
Frustrated systems exhibit remarkable properties due to the high degeneracy
of their ground states. Stabilised by competing interactions, a rich diversity
of typically nanometre-sized phase structures appear in polymer and colloidal
systems, while the surface of ice pre-melts due to geometrically frustrated
interactions. Atomic spin systems where magnetic interactions are frustrated by
lattice geometry provide a fruitful source of emergent phenomena, such as
fractionalised excitations analogous to magnetic monopoles. The degeneracy
inherent in frustrated systems may prevail all the way down to absolute zero
temperature, or it may be lifted by small perturbations or entropic effects. In
the geometrically frustrated Ising--like magnet Ca3Co2O6, we follow the
temporal and spatial evolution of nanoscale magnetic fluctuations firmly
embedded inside the spin--density--wave magnetic structure. These fluctuations
are a signature of a competing ferrimagnetic phase with an incommensurability
that is different from, but determined by the host. As the temperature is
lowered, the fluctuations slow down into a super-paramagnetic regime of stable
spatiotemporal nano-structures
Magnetic and electronic structure of the topological semimetal YbMnSb
The antiferromagnetic (AFM) semimetal YbMnSb has recently been identified
as a candidate topological material, driven by time-reversal symmetry breaking.
Depending on the ordered arrangement of Mn spins below the N\'{e}el
temperature, = 345 K, the electronic bands near the Fermi energy
can ether have a Dirac node, a Weyl node or a nodal line. We have investigated
the ground state magnetic structure of YbMnSb using unpolarized and
polarized single crystal neutron diffraction. We find that the Mn moments lie
along the axis of the space group and are arranged in a C-type AFM
structure, which implies the existence of gapped Dirac nodes near the Fermi
level. The results highlight how different magnetic structures can critically
affect the topological nature of fermions in semimetals